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Are The Basic Entities Used By Gimp

This is an image of a sheet of paper with different colors on it.

GIMP stands for GNU Image Manipulation Program. It is a free and open-source software for image editing and photo retouching. It has a wide range of features for basic to advanced users.

A layer in GIMP is a collection of graphical assets, such as photos, drawings, or photos and text layers. When you add a layer to your document, GIMP divides the document into squares that correspond to the layer’s boundaries. You can then modify the layer’s properties (such as fill color and opacity) without affecting the graphics within the other layers below it.

GIMP (GNU Image Manipulation Program) is a free and open-source graphics editor and photo retouching program. Its name is derived from the GIMP acronym for Graphics Interchange Format. It has been described as an “extremely versatile image editor”, but some people find its name offensive because it is similar to the word ‘gimp’ which is used pejoratively to describe someone who is inept or uninteresting.

GIMP is an acronym for GNU Image Manipulation Program. The name was chosen because the software is based on the GIMP image editor, which was originally written in the GNU project.

GIMP is a powerful image editor that can be used to edit, compose and publish photos on the web. It is also a versatile tool for converting files between different formats, and for creating logos, icons, and graphic designs.

Masking is a technique that allows you to hide or blur parts of an image. Masking can be used to protect the information, distort an image, or create a new image.

Opacity in GIMP is a property that allows you to control how much of your image is visible. You can set it to 100% or 0%, which means that the entire image will be visible, or you can set it to a percentage, which means that part of the image will be visible.

GIMP is an image editor that allows users to manipulate, resize, crop, and alter images using a variety of tools. The GIMP editor is popular for its ease of use and wide range of features, making it suitable for a variety of tasks from photo editing to web development.

There is no easy answer to this question as there is no single, agreed-upon definition of the word ‘gimp’. Generally speaking, though, gimp typically refers to a program or device used to make graphical alterations to images—typically in order to improve their appearance. In many cases, gimp can also be used more generally to refer to software that helps with image editing and enhancement.

It is difficult to say definitively whether or not GIMP is still active since it has not been updated in over two years. However, due to its widespread use and popularity, it is likely that GIMP is still being used by some individuals. Despite its lack of recent updates, GIMP continues to be a powerful image editing program with a large user base.

Are The Basic Entities Used By Gimp?

This section is intended to give you a brief introduction to the basic concepts and terminology you will need to understand in order to make sense of the rest of the documentation. Everything here is explained in much greater depth elsewhere. With a few exceptions, we have avoided cluttering this section with a lot of links and cross-references: everything mentioned here is so high-level that you should easily be able to locate it in the index.

The GIMP is an image manipulation program. At the most sweeping level, using GIMP involves three basic steps: (1) opening images or creating new ones; (2) altering those images; (3) saving the results.

Depending on how GIMP was started, there may already be one or more images open when you begin. You can open new images from files using the Open command from the File menu. GIMP is capable of opening a large variety of graphics file formats; see Files for more information. Depending on how your system is set up, you may also be able to open images by clicking on icons in a file manager, or by drag-and-drop from other programs. If you aren’t sure whether you can do this, just try it. The worst thing that can happen is that your computer could explode.

GIMP provides you with an enormous number of ways of acting on images: painting tools, color manipulation tools, transformation tools, filters, etc. The bulk of this manual is devoted to describing these tools and how to work with them.

When you are finished working with an image, you will want to save the results. (In fact, it is often a good idea to save at intermediate stages too: GIMP is a pretty robust program, but we have heard rumors, possibly apocryphal, that it may have been known on rare and mysterious occasions to crash.) Most of the file formats that GIMP can open, can also be used for saving. There is one file format that is special, though: XCF is GIMP ‘s native format, and is useful because it stores everything about an image (well, almost everything; it does not store “ undo ” information). Thus, the XCF format is especially suitable for saving intermediate results, and for saving images to be re-opened later in GIMP . XCF files are not readable by most other programs that display images, so once you have finished, you will probably also want to save the image in a more widely used format, such as JPEG, PNG, TIFF, etc.

Images are the basic entities that GIMP works with. Roughly speaking, an “ image ” corresponds to a single file, such as a TIFF or JPEG file. You can also think of an image as corresponding to a single display window, but this is not quite correct: it is possible to have multiple windows all displaying the same image. It is not possible to have a single window display more than one image, though, or for an image to have no window displaying it.

A GIMP image may be quite a complicated thing. Instead of thinking of it as something like a sheet of paper with a picture on it, you should think of it as more like a book, whose pages are called “ layers ” In addition to a stack of layers, a GIMP image may contain a selection mask, a set of channels, and a set of paths. In fact, GIMP provides a mechanism for attaching arbitrary pieces of data to an image, as which are called “ parasites ”

In GIMP , it is possible to have many images open at the same time. If they are large, each image may use many megabytes of memory, but GIMP uses a sophisticated tile-based memory management system that allows it to handle even very large images gracefully. There are, however, limits, and it is usually beneficial when working with images to put as much memory into your system as possible.

If an image is like a book, then a layer is like a page within the book. The simplest images only contain a single layer, and can be treated like single sheets of paper, but sophisticated GIMP users often deal with images containing many layers, even dozens of them. Layers need not be opaque, and they need not cover the entire extent of an image, so when you look at an image’s display, you may see more than just the top layer: you may see elements of many layers.

In GIMP Channels are the smallest units of subdivision in the stack of layers from which the image is constructed. Every Channel in a layer has exactly the same size as the layer it belongs to and consequently consists of the same pixels. Every pixel can be regarded as a container which can be filled with a value ranging from 0 to 255. The exact meaning of this value depends on the type of channel, e.g. in the RGB color model the value in the R -channel means the amount of red which is added to the colour of the different pixels, in the selection channel the value denotes how strong the pixels are selected and in the alpha channel the values denote how transparent the corresponding pixels are.

Often when you do something to an image, you only want a part of it to be affected. The “ selection ” mechanism makes this possible. Each image has its own selection, which you normally see as a moving dashed line separating the selected parts from the unselected parts (the so-called “ marching ants ”). Actually this is a bit misleading: selection in GIMP is really graded, not all-or-nothing, and really the selection is represented by a full-fledged grayscale channel. The dashed line that you normally see is simply a contour line at the 50%-selected level. At any time, though, you can visualize the selection channel in all its glorious detail by toggling the QuickMask button.

A large component of learning how to use GIMP effectively is acquiring the art of making good selections—selections that contain exactly what you need and nothing more. Because selection-handling is so centrally important, GIMP gives you a large number of tools for doing it: an assortment of selection-making tools, a menu of selection operations, and the ability to switch to Quick Mask mode, in which you can treat the selection channel as though it were a color channel, thereby “ painting the selection ”

When you make mistakes, you can undo them. Nearly everything you can do to an image is undoable. In fact, you can usually undo a substantial number of the most recent things you did, if you decide that they were misguided. GIMP makes this possible by keeping a history of your actions. This history consumes memory, though, so undoability is not infinite. Some actions use very little undo memory, so that you can do dozens of them before the earliest ones are deleted from this history; other types of actions require massive amounts of undo memory. You can configure the amount of memory GIMP allows for the undo history of each image, but in any situation, you should always be able to undo at least your 2-3 most recent actions. (The most important action that is not undoable is closing an image. For this reason, GIMP asks you to confirm that you really want to close the image if you have made any changes to it.)

Many, probably most, of the things you do to an image in GIMP are done by the GIMP application itself. However, GIMP also makes extensive use of “ plug-ins ” which are external programs that interact very closely with GIMP , and are capable of manipulating images and other GIMP objects in very sophisticated ways. Many important plug-ins come packaged together with GIMP , but there are also many available by other means. In fact, the ability to write plug-ins (and scripts) is the easiest way for people not on the GIMP development team to add new capabilities to GIMP .

All of the commands in the Filters menu, and a substantial number of commands in other menus, are actually implemented by plug-ins.

In addition to plug-ins, which are programs written in the C language, GIMP can also make use of scripts. The largest number of existing scripts are written in a language called Script-Fu, which is special to GIMP (for those who care, it is a dialect of the Lisp-like language called Scheme). It is also possible to write GIMP scripts in Python or Perl. These languages are more flexible and powerful than Script-Fu; their disadvantage is that they depend on software that does not automatically come packaged with GIMP, so they are not guaranteed to work correctly in every GIMP installation.

Are The Basic Entities Used By Gimp?

Рисунок 3.1. Wilber, the GIMP mascot

The Wilber Construction Kit (docs/Wilber_Construction_Kit.xcf.gz) allows you to give the mascot a different appearance. It is the work of Tuomas Kuosmanen (tigertATgimp.org).

If a simple image can be compared to a single sheet of paper, an image with layers is likened to a sheaf of transparent papers stacked one on top of the other. You can draw on each paper, but still see the content of the other sheets through the transparent areas. You can also move one sheet in relation to the others. Sophisticated GIMP users often deal with images containing many layers, even dozens of them. Layers need not be opaque, and they need not cover the entire extent of an image, so when you look at an image’s display, you may see more than just the top layer: you may see elements of many layers.

Digital images consist of a grid of square pixels. Each image has a size measured in two dimensions, such as 900 pixels wide by 600 pixels high. But pixels don’t have a set size in physical space. To set up an image for printing, we use a value called resolution, defined as the ratio between an image’s size in pixels and its physical size (usually in inches) when it is printed on paper. Most file formats (but not all) can save this value, which is expressed as ppi—pixels per inch.

When printing a file, the resolution determines the size the image will have on paper, and as a result, the physical size of the pixels. The same 900×600 pixel image may be printed as a small 3×2″ card with barely noticeable pixels—or as a large poster with large, chunky pixels.

Images imported from cameras and mobile devices tend to have a resolution attached to the file. The resolution is usually 72 or 96ppi. It is important to realize that this resolution is arbitrary and was chosen for historic reasons. You can always change the resolution with GIMP —this has no effect on the actual image pixels. Furthermore, for uses such as displaying images online, on mobile devices, television or video games—in short, any use that is not print—the resolution value is meaningless and is ignored. Instead, the image is usually displayed so that each image pixel conforms to one screen pixel.

A Channel is a single component of a pixel’s color. For a colored pixel in GIMP , these components are usually Red, Green, Blue and sometimes transparency (Alpha). For a Grayscale image, they are Gray and Alpha and for an Indexed color image, they are Indexed and Alpha.

The entire rectangular array of any one of the color components for all of the pixels in an image is also referred to as a Channel. You can see these color channels with the Channels dialog.

Channels can be useful when you are working on an image which needs adjustment in one particular color. For example, if you want to remove « red eye » from a photograph, you might work on the Red channel.

You can look at channels as masks which allow or restrict the output of the color that the channel represents. By using Filters on the channel information, you can create many varied and subtle effects on an image. A simple example of using a Filter on the color channels is the Channel Mixer filter.

Often when modifying an image, you only want a part of the image to be affected. The « selection » mechanism makes this possible. Each image has its own selection, which you normally see as a moving dashed line separating the selected parts from the unselected parts (the so-called « marching ants » ). Actually this is a bit misleading: selection in GIMP is graded, not all-or-nothing, and really the selection is represented by a full-fledged grayscale channel. The dashed line that you normally see is simply a contour line at the 50%-selected level. At any time, though, you can visualize the selection channel in all its glorious detail by toggling the QuickMask button.

All of the commands in the Filters menu, and a substantial number of commands in other menus, are actually implemented as plug-ins.

Are The Basic Entities Used By Gimp?

شكل 3.1. Wilber, the GIMP mascot

The Wilber Construction Kit (docs/Wilber_Construction_Kit.xcf.gz) allows you to give the mascot a different appearance. It is the work of Tuomas Kuosmanen (tigertATgimp.org).

If a simple image can be compared to a single sheet of paper, an image with layers is likened to a sheaf of transparent papers stacked one on top of the other. You can draw on each paper, but still see the content of the other sheets through the transparent areas. You can also move one sheet in relation to the others. Sophisticated GIMP users often deal with images containing many layers, even dozens of them. Layers need not be opaque, and they need not cover the entire extent of an image, so when you look at an image’s display, you may see more than just the top layer: you may see elements of many layers.

Digital images consist of a grid of square pixels. Each image has a size measured in two dimensions, such as 900 pixels wide by 600 pixels high. But pixels don’t have a set size in physical space. To set up an image for printing, we use a value called resolution, defined as the ratio between an image’s size in pixels and its physical size (usually in inches) when it is printed on paper. Most file formats (but not all) can save this value, which is expressed as ppi—pixels per inch.

When printing a file, the resolution determines the size the image will have on paper, and as a result, the physical size of the pixels. The same 900×600 pixel image may be printed as a small 3×2″ card with barely noticeable pixels—or as a large poster with large, chunky pixels.

Images imported from cameras and mobile devices tend to have a resolution attached to the file. The resolution is usually 72 or 96ppi. It is important to realize that this resolution is arbitrary and was chosen for historic reasons. You can always change the resolution with GIMP —this has no effect on the actual image pixels. Furthermore, for uses such as displaying images online, on mobile devices, television or video games—in short, any use that is not print—the resolution value is meaningless and is ignored. Instead, the image is usually displayed so that each image pixel conforms to one screen pixel.

A Channel is a single component of a pixel’s color. For a colored pixel in GIMP , these components are usually Red, Green, Blue and sometimes transparency (Alpha). For a Grayscale image, they are Gray and Alpha and for an Indexed color image, they are Indexed and Alpha.

The entire rectangular array of any one of the color components for all of the pixels in an image is also referred to as a Channel. You can see these color channels with the Channels dialog.

Channels can be useful when you are working on an image which needs adjustment in one particular color. For example, if you want to remove “ red eye ” from a photograph, you might work on the Red channel.

You can look at channels as masks which allow or restrict the output of the color that the channel represents. By using Filters on the channel information, you can create many varied and subtle effects on an image. A simple example of using a Filter on the color channels is the Channel Mixer filter.

Often when modifying an image, you only want a part of the image to be affected. The “ selection ” mechanism makes this possible. Each image has its own selection, which you normally see as a moving dashed line separating the selected parts from the unselected parts (the so-called “ marching ants ” ). Actually this is a bit misleading: selection in GIMP is graded, not all-or-nothing, and really the selection is represented by a full-fledged grayscale channel. The dashed line that you normally see is simply a contour line at the 50%-selected level. At any time, though, you can visualize the selection channel in all its glorious detail by toggling the QuickMask button.

All of the commands in the Filters menu, and a substantial number of commands in other menus, are actually implemented as plug-ins.

Are The Basic Entities Used By Gimp?

Pav. 3.1. Wilber, the GIMP mascot

The Wilber Construction Kit (docs/Wilber_Construction_Kit.xcf.gz) allows you to give the mascot a different appearance. It is the work of Tuomas Kuosmanen (tigertATgimp.org).

If a simple image can be compared to a single sheet of paper, an image with layers is likened to a sheaf of transparent papers stacked one on top of the other. You can draw on each paper, but still see the content of the other sheets through the transparent areas. You can also move one sheet in relation to the others. Sophisticated GIMP users often deal with images containing many layers, even dozens of them. Layers need not be opaque, and they need not cover the entire extent of an image, so when you look at an image’s display, you may see more than just the top layer: you may see elements of many layers.

Digital images consist of a grid of square pixels. Each image has a size measured in two dimensions, such as 900 pixels wide by 600 pixels high. But pixels don’t have a set size in physical space. To set up an image for printing, we use a value called resolution, defined as the ratio between an image’s size in pixels and its physical size (usually in inches) when it is printed on paper. Most file formats (but not all) can save this value, which is expressed as ppi—pixels per inch.

When printing a file, the resolution determines the size the image will have on paper, and as a result, the physical size of the pixels. The same 900×600 pixel image may be printed as a small 3×2″ card with barely noticeable pixels—or as a large poster with large, chunky pixels.

Images imported from cameras and mobile devices tend to have a resolution attached to the file. The resolution is usually 72 or 96ppi. It is important to realize that this resolution is arbitrary and was chosen for historic reasons. You can always change the resolution with GIMP —this has no effect on the actual image pixels. Furthermore, for uses such as displaying images online, on mobile devices, television or video games—in short, any use that is not print—the resolution value is meaningless and is ignored. Instead, the image is usually displayed so that each image pixel conforms to one screen pixel.

A Channel is a single component of a pixel’s color. For a colored pixel in GIMP , these components are usually Red, Green, Blue and sometimes transparency (Alpha). For a Grayscale image, they are Gray and Alpha and for an Indexed color image, they are Indexed and Alpha.

The entire rectangular array of any one of the color components for all of the pixels in an image is also referred to as a Channel. You can see these color channels with the Channels dialog.

Channels can be useful when you are working on an image which needs adjustment in one particular color. For example, if you want to remove „ red eye “ from a photograph, you might work on the Red channel.

You can look at channels as masks which allow or restrict the output of the color that the channel represents. By using Filters on the channel information, you can create many varied and subtle effects on an image. A simple example of using a Filter on the color channels is the Channel Mixer filter.

Often when modifying an image, you only want a part of the image to be affected. The „ selection “ mechanism makes this possible. Each image has its own selection, which you normally see as a moving dashed line separating the selected parts from the unselected parts (the so-called „ marching ants “ ). Actually this is a bit misleading: selection in GIMP is graded, not all-or-nothing, and really the selection is represented by a full-fledged grayscale channel. The dashed line that you normally see is simply a contour line at the 50%-selected level. At any time, though, you can visualize the selection channel in all its glorious detail by toggling the QuickMask button.

All of the commands in the Filters menu, and a substantial number of commands in other menus, are actually implemented as plug-ins.

Are The Basic Entities Used By Gimp?

Figure 3.1. Wilber, the GIMP mascot

The Wilber_Construction_Kit (in src/images/) allows you to give the mascot a different appearance. It is the work of Tuomas Kuosmanen (tigertATgimp.org).

If a simple image can be compared to a single sheet of paper, an image with layers is likened to a sheaf of transparent papers stacked one on top of the other. You can draw on each paper, but still see the content of the other sheets through the transparent areas. You can also move one sheet in relation to the others. Sophisticated GIMP users often deal with images containing many layers, even dozens of them. Layers need not be opaque, and they need not cover the entire extent of an image, so when you look at an image’s display, you may see more than just the top layer: you may see elements of many layers.

Digital images comprise of a grid of square elements of varying colors, called pixels. Each image has a pixel size, such as 900 pixels wide by 600 pixels high. But pixels don’t have a set size in physical space. To set up an image for printing, we use a value called resolution, defined as the ratio between an image’s size in pixels and its physical size (usually in inches) when it is printed on paper. Most file formats (but not all) can save this value, which is expressed as ppi — pixels per inch. When printing a file, the resolution value determines the size the image will have on paper, and as a result, the physical size of the pixels. The same 900×600 pixel image may be printed as a small 3×2″ card with barely noticeable pixels — or as a large poster with large, chunky pixels. Images imported from cameras and mobile devices tend to have a resolution value attached to the file. The value is usually 72 or 96ppi. It is important to realize that this value is arbitrary and was chosen for historic reasons. You can always change the resolution value inside GIMP — this has no effect on the actual image pixels. Furthermore, for uses such as displaying images on line, on mobile devices, television or video games — in short, any use that is not print — the resolution value is meaningless and is ignored, and instead the image is usually displayed so that each image pixel conforms to one screen pixel.

A Channel is a single component of a pixel’s color. For a colored pixel in GIMP , these components are usually Red, Green, Blue and sometimes transparency (Alpha). For a Grayscale image, they are Gray and Alpha and for an Indexed color image, they are Indexed and Alpha.

The entire rectangular array of any one of the color components for all of the pixels in an image is also referred to as a Channel. You can see these color channels with the Channels dialog.

Channels can be useful when you are working on an image which needs adjustment in one particular color. For example, if you want to remove “ red eye ” from a photograph, you might work on the Red channel.

You can look at channels as masks which allow or restrict the output of the color that the channel represents. By using Filters on the channel information, you can create many varied and subtle effects on an image. A simple example of using a Filter on the color channels is the Channel Mixer filter.

Often when modify an image, you only want a part of the image to be affected. The “ selection ” mechanism makes this possible. Each image has its own selection, which you normally see as a moving dashed line separating the selected parts from the unselected parts (the so-called “ marching ants ” ). Actually this is a bit misleading: selection in GIMP is graded, not all-or-nothing, and really the selection is represented by a full-fledged grayscale channel. The dashed line that you normally see is simply a contour line at the 50%-selected level. At any time, though, you can visualize the selection channel in all its glorious detail by toggling the QuickMask button.

All of the commands in the Filters menu, and a substantial number of commands in other menus, are actually implemented as plug-ins.

Are The Basic Entities Used By Gimp?

Figure 3.1. Wilber, the GIMP mascot

The Wilber Construction Kit (docs/Wilber_Construction_Kit.xcf.gz) allows you to give the mascot a different appearance. It is the work of Tuomas Kuosmanen (tigertATgimp.org).

If a simple image can be compared to a single sheet of paper, an image with layers is likened to a sheaf of transparent papers stacked one on top of the other. You can draw on each paper, but still see the content of the other sheets through the transparent areas. You can also move one sheet in relation to the others. Sophisticated GIMP users often deal with images containing many layers, even dozens of them. Layers need not be opaque, and they need not cover the entire extent of an image, so when you look at an image’s display, you may see more than just the top layer: you may see elements of many layers.

Digital images consist of a grid of square pixels. Each image has a size measured in two dimensions, such as 900 pixels wide by 600 pixels high. But pixels don’t have a set size in physical space. To set up an image for printing, we use a value called resolution, defined as the ratio between an image’s size in pixels and its physical size (usually in inches) when it is printed on paper. Most file formats (but not all) can save this value, which is expressed as ppi—pixels per inch.

When printing a file, the resolution determines the size the image will have on paper, and as a result, the physical size of the pixels. The same 900×600 pixel image may be printed as a small 3×2″ card with barely noticeable pixels—or as a large poster with large, chunky pixels.

Images imported from cameras and mobile devices tend to have a resolution attached to the file. The resolution is usually 72 or 96ppi. It is important to realize that this resolution is arbitrary and was chosen for historic reasons. You can always change the resolution with GIMP —this has no effect on the actual image pixels. Furthermore, for uses such as displaying images online, on mobile devices, television or video games—in short, any use that is not print—the resolution value is meaningless and is ignored. Instead, the image is usually displayed so that each image pixel conforms to one screen pixel.

A Channel is a single component of a pixel’s color. For a colored pixel in GIMP , these components are usually Red, Green, Blue and sometimes transparency (Alpha). For a Grayscale image, they are Gray and Alpha and for an Indexed color image, they are Indexed and Alpha.

The entire rectangular array of any one of the color components for all of the pixels in an image is also referred to as a Channel. You can see these color channels with the Channels dialog.

Channels can be useful when you are working on an image which needs adjustment in one particular color. For example, if you want to remove “ red eye ” from a photograph, you might work on the Red channel.

You can look at channels as masks which allow or restrict the output of the color that the channel represents. By using Filters on the channel information, you can create many varied and subtle effects on an image. A simple example of using a Filter on the color channels is the Channel Mixer filter.

Often when modifying an image, you only want a part of the image to be affected. The “ selection ” mechanism makes this possible. Each image has its own selection, which you normally see as a moving dashed line separating the selected parts from the unselected parts (the so-called “ marching ants ” ). Actually this is a bit misleading: selection in GIMP is graded, not all-or-nothing, and really the selection is represented by a full-fledged grayscale channel. The dashed line that you normally see is simply a contour line at the 50%-selected level. At any time, though, you can visualize the selection channel in all its glorious detail by toggling the QuickMask button.

All of the commands in the Filters menu, and a substantial number of commands in other menus, are actually implemented as plug-ins.

Are The Basic Entities Used By Gimp?

图 3.1. Wilber, the GIMP mascot

The Wilber Construction Kit (docs/Wilber_Construction_Kit.xcf.gz) allows you to give the mascot a different appearance. It is the work of Tuomas Kuosmanen (tigertATgimp.org).

If a simple image can be compared to a single sheet of paper, an image with layers is likened to a sheaf of transparent papers stacked one on top of the other. You can draw on each paper, but still see the content of the other sheets through the transparent areas. You can also move one sheet in relation to the others. Sophisticated GIMP users often deal with images containing many layers, even dozens of them. Layers need not be opaque, and they need not cover the entire extent of an image, so when you look at an image’s display, you may see more than just the top layer: you may see elements of many layers.

Digital images consist of a grid of square pixels. Each image has a size measured in two dimensions, such as 900 pixels wide by 600 pixels high. But pixels don’t have a set size in physical space. To set up an image for printing, we use a value called resolution, defined as the ratio between an image’s size in pixels and its physical size (usually in inches) when it is printed on paper. Most file formats (but not all) can save this value, which is expressed as ppi—pixels per inch.

When printing a file, the resolution determines the size the image will have on paper, and as a result, the physical size of the pixels. The same 900×600 pixel image may be printed as a small 3×2″ card with barely noticeable pixels—or as a large poster with large, chunky pixels.

Images imported from cameras and mobile devices tend to have a resolution attached to the file. The resolution is usually 72 or 96ppi. It is important to realize that this resolution is arbitrary and was chosen for historic reasons. You can always change the resolution with GIMP —this has no effect on the actual image pixels. Furthermore, for uses such as displaying images online, on mobile devices, television or video games—in short, any use that is not print—the resolution value is meaningless and is ignored. Instead, the image is usually displayed so that each image pixel conforms to one screen pixel.

A Channel is a single component of a pixel’s color. For a colored pixel in GIMP , these components are usually Red, Green, Blue and sometimes transparency (Alpha). For a Grayscale image, they are Gray and Alpha and for an Indexed color image, they are Indexed and Alpha.

The entire rectangular array of any one of the color components for all of the pixels in an image is also referred to as a Channel. You can see these color channels with the Channels dialog.

Channels can be useful when you are working on an image which needs adjustment in one particular color. For example, if you want to remove “ red eye ” from a photograph, you might work on the Red channel.

You can look at channels as masks which allow or restrict the output of the color that the channel represents. By using Filters on the channel information, you can create many varied and subtle effects on an image. A simple example of using a Filter on the color channels is the Channel Mixer filter.

Often when modifying an image, you only want a part of the image to be affected. The “ selection ” mechanism makes this possible. Each image has its own selection, which you normally see as a moving dashed line separating the selected parts from the unselected parts (the so-called “ marching ants ” ). Actually this is a bit misleading: selection in GIMP is graded, not all-or-nothing, and really the selection is represented by a full-fledged grayscale channel. The dashed line that you normally see is simply a contour line at the 50%-selected level. At any time, though, you can visualize the selection channel in all its glorious detail by toggling the QuickMask button.

All of the commands in the Filters menu, and a substantial number of commands in other menus, are actually implemented as plug-ins.

Are The Basic Entities Used By Gimp?

Figur 3.1. Wilber, the GIMP mascot

The Wilber Construction Kit (docs/Wilber_Construction_Kit.xcf.gz) allows you to give the mascot a different appearance. It is the work of Tuomas Kuosmanen (tigertATgimp.org).

If a simple image can be compared to a single sheet of paper, an image with layers is likened to a sheaf of transparent papers stacked one on top of the other. You can draw on each paper, but still see the content of the other sheets through the transparent areas. You can also move one sheet in relation to the others. Sophisticated GIMP users often deal with images containing many layers, even dozens of them. Layers need not be opaque, and they need not cover the entire extent of an image, so when you look at an image’s display, you may see more than just the top layer: you may see elements of many layers.

Digital images consist of a grid of square pixels. Each image has a size measured in two dimensions, such as 900 pixels wide by 600 pixels high. But pixels don’t have a set size in physical space. To set up an image for printing, we use a value called resolution, defined as the ratio between an image’s size in pixels and its physical size (usually in inches) when it is printed on paper. Most file formats (but not all) can save this value, which is expressed as ppi—pixels per inch.

When printing a file, the resolution determines the size the image will have on paper, and as a result, the physical size of the pixels. The same 900×600 pixel image may be printed as a small 3×2″ card with barely noticeable pixels—or as a large poster with large, chunky pixels.

Images imported from cameras and mobile devices tend to have a resolution attached to the file. The resolution is usually 72 or 96ppi. It is important to realize that this resolution is arbitrary and was chosen for historic reasons. You can always change the resolution with GIMP —this has no effect on the actual image pixels. Furthermore, for uses such as displaying images online, on mobile devices, television or video games—in short, any use that is not print—the resolution value is meaningless and is ignored. Instead, the image is usually displayed so that each image pixel conforms to one screen pixel.

A Channel is a single component of a pixel’s color. For a colored pixel in GIMP , these components are usually Red, Green, Blue and sometimes transparency (Alpha). For a Grayscale image, they are Gray and Alpha and for an Indexed color image, they are Indexed and Alpha.

The entire rectangular array of any one of the color components for all of the pixels in an image is also referred to as a Channel. You can see these color channels with the Channels dialog.

Channels can be useful when you are working on an image which needs adjustment in one particular color. For example, if you want to remove “ red eye ” from a photograph, you might work on the Red channel.

You can look at channels as masks which allow or restrict the output of the color that the channel represents. By using Filters on the channel information, you can create many varied and subtle effects on an image. A simple example of using a Filter on the color channels is the Channel Mixer filter.

Often when modifying an image, you only want a part of the image to be affected. The “ selection ” mechanism makes this possible. Each image has its own selection, which you normally see as a moving dashed line separating the selected parts from the unselected parts (the so-called “ marching ants ” ). Actually this is a bit misleading: selection in GIMP is graded, not all-or-nothing, and really the selection is represented by a full-fledged grayscale channel. The dashed line that you normally see is simply a contour line at the 50%-selected level. At any time, though, you can visualize the selection channel in all its glorious detail by toggling the QuickMask button.

All of the commands in the Filters menu, and a substantial number of commands in other menus, are actually implemented as plug-ins.

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