How to Understand Pixels, Resolution, and Resize Your Images in Photoshop Correctly
- 1 How to Understand Pixels, Resolution, and Resize Your Images in Photoshop Correctly
- 2 How to Understand Pixels, Resolution, and Resize Your Images in Photoshop Correctly
- 3 Get More Accurate Print Size Previews In Photoshop
- 4 Image Resolution, Pixel Dimensions and Document Size in Photoshop
- 5 About monitor resolution
- 6 Using the Crop tool
- 7 About printer resolution
- 8 Contents
- 9 Article Description
- 10 From the book
- 11 Strategy for retouching
How to Understand Pixels, Resolution, and Resize Your Images in Photoshop Correctly
Size, resolution, and formats… What do pixels have to do with it?
Do you buy your camera based on its number of megapixels? Are you having problems sharing your photos online? Does your print look low quality even if it looks great on the screen? There seems to be a lot of confusion between pixels and bytes (image size and file size), quality and quantity, size, and resolution.
So let’s review some basics to make your life easier, your workflow more efficient, and your images the correct size for the intended usage.
This image is sized to 750×500 pixels at 72 dpi, saved as a compressed JPG which is 174kb. Let’s look at what all that means.
Get More Accurate Print Size Previews In Photoshop
In a previous tutorial, The 72 ppi Web Resolution Myth, we looked at a belief held by many digital photographers and web designers today that images destined for the web or for viewing on-screen need to be saved in Photoshop at a resolution of 72 pixels per inch. Some believe it allows their images to display properly on the web. Others believe a 72 ppi resolution prevents people from downloading and printing high quality versions of the image. However, we learned in that tutorial that neither of these reasons hold true, and that 72 ppi hasn’t actually been a useful “standard” in over 20 years!
As we learned in that tutorial, computer displays today all have screen resolutions higher than 72 pixels per inch, and we proved it by learning an easy way to find your monitor’s actual screen resolution. In this tutorial, we’ll learn how to take that information, give it to Photoshop, and enjoy much more accurate on-screen previews of how our photos will look when printed!
Version Requirements: To get the most from this tutorial, you’ll need to be using Photoshop CS4 or higher and that’s because we’ll be using a feature that Adobe first introduced in CS4. It is not available in CS3 or earlier. I’ll be using Photoshop CS6 here but any version from CS4 and up will do.
The Problem With Photoshop’s Print Size View
Photoshop lets us view our images at just about any zoom size we like using the Zoom Tool, and it also includes a few automatic zoom options under the View menu in the Menu Bar, like Fit on Screen, which zooms the image to whatever size is needed for it to fit entirely within the dimensions of your display, and Actual Pixels which instantly jumps you to the 100% zoom level.
Yet one zoom option under the View menu has remained a mystery to most Photoshop users over the years – Print Size. I’m calling it a “mystery” to be polite, but most Photoshop users simply call it “useless”, a more accurate description. At least, it’s accurate if you don’t know the two important things we’re about to learn – why it’s useless and how to fix it!
Like Apple’s original 72 pixel-per-inch screen resolution standard from nearly 30 years ago, the goal of Photoshop’s Print Size view mode was to give us an accurate preview of how the image on your screen will look when printed. The way it’s supposed to work is that when we choose the Print Size command from the View menu, Photoshop instantly zooms the image to whatever level is needed for it to appear on your screen at the same size it will appear on paper. For example, if you’re working on an image that will be printed as a 4×6, the Print Size command would display the image 4 inches x 6 inches on your screen. Not only would this help you visualize the final printed result, it would also help when sharpening the image for output. At least, that was the plan.
Here’s the problem. In order for the plan to work, Photoshop needs to know your computer display’s screen resolution so it can do the math and figure out the correct zoom level, but Photoshop doesn’t know your display’s screen resolution and it has no way of finding that out on its own. So what does it do? It just assumes your screen resolution is that good ol’ 72 pixels per inch nonsense when it’s really much higher than that. What happens when we do the math using the wrong numbers? We get the wrong answer, and in the case of the Print Size view mode, Photoshop ends up choosing the wrong zoom level, resulting in a print size preview that’s not even close to being accurate.
As an example, here’s an image I currently have open in Photoshop. At the moment, it’s being viewed at the 100% zoom level (young thinking woman photo from Shutterstock):
I’ll open my Image Size dialog box by going up to the Image menu in the Menu Bar along the top of the screen and choosing Image Size:
Here, in the Document Size section of the Image Size dialog box, where we set the size and resolution of the printed version of the image, we see that my image is current set to print as a 4×6 (6 inches for the width, 4 inches for the height):
Now that we know how large the image will print, I’ll click OK to close out of the Image Size dialog box, and then I’ll choose Photoshop’s Print Size view mode by going up to the View menu at the top of the screen and choosing Print Size:
According to how the Print Size view mode is supposed to work, Photoshop should instantly jump to whatever zoom level is needed for the image to appear on my screen at the same size it will print, which in this case would be 6 inches across and 4 inches from top to bottom. In other words, I should be able to grab an actual 4×6 photo, hold it up to my screen and see that the size of the image on my screen in Photoshop now matches the size of the photo.
And yet, that’s not the case. My image is not being displayed at 6 inches x 4 inches on my screen. It’s actually being displayed much smaller. If I grab a ruler, I can quickly measure it and see that it appears roughly 3.8 inches across and 2.5 inches top to bottom. That’s not even close to being an accurate on-screen preview of the print size:
Let’s look down in the bottom left corner of the interface where we see that Photoshop has set the zoom level of my image to 24%. This, according to Photoshop, is the correct zoom level for making my image appear 6×4 inches on my screen. That’s great, except that it’s obviously wrong. Why is it wrong? It’s because Photoshop is wrongly assuming that my computer monitor’s screen resolution is 72 pixels per inch:
Finding Your Actual Screen Resolution
How do we fix that? We find out what our computer display’s actual screen resolution is and then we give that information to Photoshop. First, we need to find our screen resolution using a simple test. If you’ve already done this step from the previous tutorial and you have the information handy, you can skip this part and move on to the next step.
To find your display’s screen resolution, grab a ruler or tape measure (a tape measure is probably easier). Then, measure the screen’s width, in inches, from left to right. Don’t include any of the border area around the screen. Measure only the screen itself. If you need to, round the measurement off to a single decimal place. In my case, my screen’s width is 23.4 inches, but of course yours may be different (computer monitor photo from Shutterstock):
Next, make sure your computer monitor is running at its native display resolution, which gives you the actual number of pixels in your display from left to right and top to bottom. For example, a screen with a native display resolution of 1920×1080 has 1920 pixels from left to right and 1080 from top to bottom. The monitor I’m using runs at 2560×1440. Whatever your monitor’s native display resolution is, make sure it’s what you have it set to in your operating system’s display options.
Then, simply take the first number in your monitor’s native display resolution, which gives you the screen width in pixels, and divide it by your measured screen width in inches. This will give you the actual screen resolution in pixels per inch. For example, I’ll take the first number in my display resolution, 2560, and divide it by my measured screen width in inches, which was 23.4. Using my operating system’s handy built-in calculator, 2560 ÷ 23.4 = 109.4, which I’ll round off to 109. So, using this easy test, I’ve quickly figured out that my display’s screen resolution is 109 pixels per inch, not 72 pixels per inch like Photoshop had assumed. Again, your screen resolution may be different, but it will certainly be higher than 72 ppi.
Giving The Screen Resolution To Photoshop
Now that we have our actual screen resolution, we need to enter it into Photoshop and we do that in the Preferences. On a Windows PC, go up to the Edit menu at the top of the screen, choose Preferences way down at the bottom of the list, and then choose Units & Rulers. On a Mac, go up to the Photoshop menu, choose Preferences, then choose Units & Rulers:
This opens the Preferences dialog box set to the Units & Rulers preferences, and here’s where we find the problem. The Screen Resolution option (directly below the Print Resolution option that we don’t need to worry about) is set by default to 72 pixels per inch, which is why the Print Size view mode isn’t working properly:
To fix the problem, simply replace the 72 with your correct screen resolution. In my case, it’s 109:
Enabling OpenGL (Photoshop CS4 And Higher)
Don’t close out of the Preferences dialog box just yet because there’s one more quick thing we need to do. Select Performance in the list of preference categories along the left of the dialog box:
If you’re using Photoshop CS6 as I am, make sure the Use Graphics Processor option is checked (in Photoshop CS4 and CS5, the option is called Enable OpenGL Drawing). This allows Photoshop to access the OpenGL capabilities of your video card for advanced, hardware-accelerated screen rendering. There’s a whole list of features this enables in Photoshop, but the one we’re most interested in here is that it helps display a sharper, more accurate image at zoom levels other than 100% (like our Print Size zoom level, for example). Note that if, for whatever reason, the option was not enabled and you just enabled it now, you’ll need to close out of any open documents in Photoshop and then re-open them for OpenGL to take effect:
Trying The Print Size View Mode Again
Once you’ve entered in your actual screen resolution and made sure the OpenGL feature is enabled, go ahead and close out of the Preferences dialog box. You should now have a working Print Size view mode! To test it, I’ll once again go up to View menu at the top of the screen and choose Print Size:
And this time, now that Photoshop knows what my actual screen resolution is, it’s able to figure out the correct zoom level for my image to display 6 inches x 4 inches on my screen. This, combined with the OpenGL features we made sure were enabled in the Performance preferences, gives me a much more accurate preview of what my image will look like when printed:
If you remember, back when Photoshop was still thinking my screen resolution was 72 ppi, it chose an incorrect zoom level of 24% for the Print Size view mode. This time, knowing what my screen resolution really is, it was able to select a more accurate zoom level of 36.33% (yours may be different):
And there we have it! That’s how to easily find your display’s actual screen resolution (not 72 ppi), enter it into the Preferences, and get more accurate on-screen results from the Print Size view mode in Photoshop!
Image Resolution, Pixel Dimensions and Document Size in Photoshop
A lot of people, whether new to Photoshop or not, are confused by the term “image resolution”.
Question: “Is it like a New Years’ Resolution where I have to give something up for a month?”
Answer: “Nope, not that kind of resolution. And, I think you’re actually supposed to give something up for longer than a month. But no, that’s not it.”
Question: “What about, like, ‘resolving’ a problem? That sort of resolution?”
Answer: “Nope. Well, kinda, in the sense that understanding image resolution can definitely solve a lot of problems. But really, no.”
Question: “Hmm. Oh, I know! You mean, like, Prince & The Resolution, from the 80’s – Purple Rain, Let’s Go Crazy, that sort of thing?”
Answer: “Umm. no. And, you’re thinking of “Revolution”, not resolution. Still, no, that’s not it either.”
So if it’s not something you give up, has nothing to do with resolving an issue, and doesn’t involve doves crying or partying like it’s 1999, then what exactly is “image resolution”? Well, let me throw one more thing in there that image resolution has nothing to do with, and that’s how your image looks on your computer screen. That’s right, the resolution of your image has absolutely nothing to do with how your image appears on screen. It does, however, have everything to do with how your image will print.
Let’s repeat that one more time. Image resolution has absolutely nothing to do with how your image looks on screen. It has everything to do with how it will print. Let’s examine things further.
Here’s a photo I took one day while strolling through a park. I saw this little guy (or girl, who knows) posing for me on the flowers and happened to have my camera handy. My camera, by the way, is an 8MP camera, and the reason why I’m telling you this will be explained shortly.
Obviously, the photo you’re seeing above is a much smaller version of the photo, since the actual-size version would be too large to fit on the screen. Let’s pretend though for the sake of this lesson that we’re working with the full size version of the photo. In order to see exactly how large the photo is, once we have it open inside Photoshop, we can simply go up to the Image menu at the top of the screen and choose Image Size from the list of options, which will bring up Photoshop’s Image Size dialog box, as shown below.
The Image Size dialog box can seem a bit frightening and confusing, but it’s not meant to be and really, it’s quite simple. It’s divided into two sections, Pixel Dimensions and Document Size. For the moment, let’s ignore the Document Size part and focus only on Pixel Dimensions.
The term “pixel dimensions” here, to me, is confusing because it sounds like we’re talking about the dimensions of each individual pixel, and that’s not the case. What Photoshop is really telling us is the width and height of our image in pixels. In other words, how many pixels are in our image from left to right, and how many pixels are in our image from top to bottom. It’s also telling us one other important piece of information which is the file size of our image. The dimensions and file size shown here are of the full size version of the photo above (the insect on the flower) before I resized it to something more suitable for a web page. So here, Photoshop is telling me that my photo has a width of 3456 pixels and a height of 2304 pixels. In other words, it contains 3456 pixels from left to right, and 2304 pixels from top to bottom. To find out exactly how many pixels I have in my photo then, I can simply multiply the width times the height, which in this case is 3456 x 2304, which gives me a grand total of 7,962,624 pixels. That’s a whole lot of pixels.
Remember earlier when I mentioned that the camera I used to take this photo was an 8MP camera? Well, the “MP” stands for “mega pixel”, and “mega” means “million”, so “8MP” means 8 million pixels. This means that when I take a photo with my digital camera, the photo will be made up of 8 million pixels (approximately, anyway). If you have a 5MP camera, your photos will be made up of 5 million pixels. 4MP cameras give you photos made up of 4 million pixels, and so on. So if we take a look again at what the Pixel Dimensions section of the Image Size dialog box is telling us about my photo above, it’s saying that my photo has dimensions of 3456 pixels wide by 2304 pixels high, for a total of 7,962,624 pixels, which is pretty darn close to 8 million, and that’s why my camera can be sold as an 8MP camera.
So that’s what the first part of the Image Size dialog box is telling us – the width and height of our image in pixels. So far so good. Let’s take a look now at the second part of the dialog box, Document Size, which is where we really start to make sense of image resolution.
So far in our look at image resolution, we examined the first section of the Image Size dialog box in Photoshop, “Pixel Dimensions”, which, as a quick recap, tells us the width and height of our image in pixels, and tells us the file size, which is usually in MB (megabytes, or “millions of bytes”). Nothing terribly confusing here.
The second section of the Image Size dialog box is “Document Size”, which can be a bit more confusing but really isn’t much more complicated than the Pixel Dimensions section. In fact, the two of them go hand in hand. Let’s take a look at the Document Size section, and by the time we’re done, you should have a pretty good grasp on the difference between the two and on image resolution itself.
Document Size goes hand in hand with Pixel Dimensions, yet is also completely separate from it. “Gee thanks, that really cleared it up,” you’re saying. I know it sounds confusing, but bare with me for a moment. Notice at the bottom of the Document Size section, it says “Resolution”, and in the Resolution box, it says “72”. Notice also to the right of that is another box, this one saying “pixels/inch”.
What this is telling us is that when we go to print the photo, 72 pixels out of our 3456 pixels from left to right in our photo (the width), and 72 pixels out of our 2304 pixels from top to bottom in our photo (the height), will be printed for every one inch of paper. That’s what “image resolution” means – how many of your image’s pixels left to right and how many of the pixels top to bottom will print in every inch of paper. Of course, an inch is a square, which means the number of pixels from left to right and top to bottom will always be the same, and that’s why the Document Size section contains only one number for Resolution. That number (72 here) represents both the left to right and top to bottom number.
So, if we have 3456 pixels from left to right in our photo, and 2304 pixels from top to bottom in our photo, and we have 72 pixels per inch listed for the resolution of our image, how large will our image actually be if we were to print it? Well, to figure that out, all we need to do is divide the width and height of our image (in pixels) by the print resolution (also in pixels). So let’s do that:
3456 divided by 72 = 48
2304 divided by 72 = 32
After our simple math (yes I know, math sucks but this one’s easy), we find out that at a print resolution of 72 pixels per inch, our photo is going to be 48 inches wide by 32 inches high. That’s a huge photo! But wait a minute, didn’t we see those numbers 48 and 32 somewhere before? Why yes we did. Take a look once again at the Document Size section:
Look what values it’s giving us for the width and height of our image – 48 inches for the width, and 32 inches for the height. Exactly what we came up with ourselves when we divided the number of pixels wide and the number of pixels high by 72 pixels per inch (the resolution). And that’s really all that image resolution is. It’s how many if your image’s pixels will print inside every inch of paper, which then tells us how large the image will be when it’s printed.
Keep in mind as we’re going along that I keep saying “printed”. I can’t stress enough, and this is the number one reason why so many people have a difficult time grasping the concept of image resolution, that resolution means absolutely nothing until you go to print the image. It has absolutely nothing to do with how your image appears on your screen.
Just to prove there’s nothing up my sleeve, let’s change the resolution value of the photo from 72 to, oh, let’s make it 300, which will mean that for every inch of paper when we go to print our image, 300 of our image’s pixels will be printed from left to right and 300 again from top to bottom. You can see the change in the screenshot below:
Now, since 300 of our image’s pixels from left to right are going to be fitting inside every inch of paper as opposed to only 72 pixels, it stands to reason that it’s not going to take 48 inches of paper to fit the entire width of our photo into. Likewise, since 300 of our pixels from top to bottom are going to be fitting inside every inch of paper as opposed to only 72 pixels, it shouldn’t still take 32 inches of paper to fit the entire height into. Just for fun, let’s do the simple math ourselves. Once again, all we need to do is divide the width in pixels and the height in pixels by the resolution in pixels. So let’s do that:
3456 divided by 300 = 11.52
2304 divided by 300 = 7.68
According to my math, when I take 3456 pixels wide and divide them by 300 pixels per inch, that gives me 11.52 inches. Likewise, 2304 pixels high divided by 300 pixels per inch gives me 7.68 inches. In other words, when I take my photo that’s 3456 pixels wide by 2304 pixels high and print it at a resolution of 300 pixels per inch, my photo will be 11.52 inches wide by 7.68 pixels high. Let’s take a look at what the Document Size section is telling us. Am I right?
Looks like my math skills are stronger than ever (okay, so I used a calculator). Photoshop is showing us exactly what we expected, that at a resolution of 300 pixels per inch, it will take 11.52 inches wide and 7.68 pixels high to print our entire photo.
To summarize then, all “image resolution” means is how many of your image’s pixels will print inside every inch of paper. Again, it has no effect at all on how your image appears on your screen, since your monitor has nothing to do with your printer.
There’s one other aspect that image resolution has to do with, and that’s the size of the pixels when you go to print the image. It makes sense, really. An inch is an inch is an inch. The size of an inch is always the same. It’s, well, one inch. So, since the size of an inch can’t change, the size of the pixels has to change. For example, in order to fit 300 pixels into an inch, you would need pixels that are considerably smaller than if you only wanted to fit 72 pixels into an inch. Sort of like how, if you wanted to fit 10 people into a phone booth, you’d need people who were considerably smaller than if you only wanted to fit 3 people in there. Fortunately, you don’t need to worry about that. Photoshop takes care of resizing the pixels for us. I just wanted to explain that “image resolution” really means two things – the number of pixels per inch that will be printed on the paper, and the size of those pixels. As I said though, Photoshop takes care of sizing them for us. All we need to do is make sure we’re using the correct value for “pixels per inch”.
“Hey, wait a minute!” you’re thinking. “Correct value?! What correct value? There’s an actual number I’m supposed to use for resolution that’s ‘correct’?!”
Yep, there sure is. Well, if you’re concerned about image quality, anyway (and of course you are). We look at the “correct” resolution values to add for maximum image quality when printing in our next section – How Image Resolution Affects Print Quality.
A good resolution for Photoshop is 300 pixels per inch. This will ensure that your images are high quality and look great when printed.
The default resolution for Photoshop is 300 pixels per inch.
To change the resolution in Photoshop, go to Image > Image Size. In the Resolution section, change the resolution to 1920×1080 and click OK.
300 DPI is not high resolution. It is a common printing resolution, but it is not high resolution. For comparison, a typical high-resolution image might have a resolution of 3,000 or 4,000 DPI.
1920×1080 is a resolution for displays, meaning it is the number of pixels wide and high that the display can show. Most HDTVs use this resolution.
You would need at least a 96 DPI monitor for 1920×1080 resolution. Anything less and the text and images on the screen will be too small to see clearly.
PPI (pixels per inch) is the resolution at which an image is printed. A higher PPI means a higher quality print. DPI (dots per inch) is the resolution at which an image is displayed on a screen. A higher DPI means a sharper image. Photoshop measures resolution in PPI, but most other programs measure it in DPI.
1080p is a resolution of 1920×1080 pixels.
You would need at least a 96 DPI monitor for 1920×1080 resolution. Anything less and the text and images on the screen will be too small to see clearly.
The pixel size is the resolution of an image in terms of the number of individual pixels it contains. In general, the higher the pixel size, the sharper the image will be.
There is no definitive answer to this question as it depends on individual preferences and uses. In general, 1920×1080 is considered to be a higher resolution than 1080p, so it may be better for certain applications or users. However, 1080p is still a very popular resolution and many people are happy with the results they get from it. Ultimately, it is up to the individual to decide which resolution is best for them.
There is no definitive answer to this question as it depends on individual preferences and what the user plans to use the television for. 1080p televisions typically offer a higher resolution than 720p televisions, so images and text may appear sharper. However, 720p televisions are often cheaper than their 1080p counterparts, so some consumers may prefer to purchase a 720p television in order to save money. Ultimately, it is up to the individual to decide which resolution is best for them.
1920×1080 is a good resolution for most displays. It provides a good balance between screen size and image quality.
There is no definitive answer to this question as it depends on the specific needs of the user. 300 DPI is generally considered sufficient for most printing needs, but some users may find that 600 DPI provides a higher level of detail.
There is no definitive answer to this question as it depends on the specific needs of the user. In general, 300dpi is considered to be a higher quality resolution than 72dpi, but there are many factors that can affect the final decision. Some considerations might include the intended use of the image (printing vs. displaying online), the size of the image, and the level of detail required.
About monitor resolution
Your monitor’s resolution is described in pixel dimensions. For example, if your monitor resolution is set to 1600 x 1200 and your photo’s pixel dimensions are the same size, at 100%, the photo will fill the screen. The size an image appears onscreen depends on a combination of factors: the pixel dimensions of the image, the monitor size, and the monitor resolution setting. In Photoshop Elements, you can change the image magnification onscreen, so you can easily work with images of any pixel dimensions.
When preparing images for onscreen viewing, you should consider the lowest monitor resolution that your photo is likely to be viewed on.
Using the Crop tool
When you use the Crop tool to resize an image, the pixel dimensions and the file size change but the image isn’t resampled. When you use the Crop tool, the pixel dimensions and resolution incorporate more pixels per inch based on the size of the crop region. However, Photoshop isn’t specifically adding or removing data from the image.
When you crop an image, you remove data from or add data to the original image size to create a different image. Because you are removing or adding data relative to the original image, the concept of resampling loses much of its meaning. That’s because the number of pixels per inch can vary based on the number of pixels in the crop selection area. When the number of pixels in the crop area allows, Photoshop tries to keep the same resolution of the original image. This method is considered cropping without resampling. However, when you are not exact about the number of pixels you select, the pixel dimensions and file size changes in the new image.
About printer resolution
Printer resolution is measured in ink dots per inch, also known as dpi. Generally, the more dots per inch, the finer the printed output you’ll get. Most inkjet printers have a resolution of approximately 720 to 2880 dpi. (Technically, inkjet printers produce a microscopic spray of ink, not actual dots like imagesetters or laser printers.)
Printer resolution is different from, but related to image resolution. To print a high quality photo on an inkjet printer, an image resolution of at least 220 ppi should provide good results.
Screen frequency is the number of printer dots or halftone cells per inch used to print grayscale images or color separations. Also known as screen ruling or line screen, screen frequency is measured in lines per inch (lpi)—or lines of cells per inch in a halftone screen. The higher the resolution of the output device, the finer (higher) a screen ruling you can use.
The relationship between image resolution and screen frequency determines the quality of detail in the printed image. To produce a halftone image of the highest quality, you generally use an image resolution that is from 1.5 to at most 2 times the screen frequency. But with some images and output devices, a lower resolution can produce good results. To determine your printer’s screen frequency, check your printer documentation or consult your service provider.
Some imagesetters and 600‑dpi laser printers use screening technologies other than halftoning. If you are printing an image on a nonhalftone printer, consult your service provider or your printer documentation for the recommended image resolutions.
A. 65 lpi: Coarse screen typically used to print newsletters and grocery coupons B. 85 lpi: Average screen typically used to print newspapers C. 133 lpi: High-quality screen typically used to print four-color magazines D. 177 lpi: Very fine screen typically used for annual reports and images in art books
- 2. Basic Photo Corrections
- Resolution and image size
- Getting started
- Adjusting the color in Camera Raw
- Straightening and cropping the image in Photoshop
- Replacing colors in an image
- Adjusting saturation with the Sponge tool
- Repairing areas with the Clone Stamp tool
- Using the Spot Healing Brush tool
- Applying a content-aware patch
From the book
Note: This excerpt does not include the lesson files. The lesson files are available with purchase of the book.
In this lesson, you’ll learn how to do the following:
- Understand image resolution and size.
- Open and edit an image in Camera Raw.
- Adjust the tonal range of an image.
- Straighten and crop an image.
- Paint over a color with the Color Replacement tool.
- Adjust the saturation of isolated areas of an image using the Sponge tool.
- Use the Clone Stamp tool to eliminate an unwanted part of an image.
- Use the Spot Healing Brush tool to repair part of an image.
- Use the content-aware Patch tool to remove blemishes.
- Apply the Unsharp Mask filter to finish retouching photos.
- Save an image file for use in a page layout application.
This lesson will take about an hour to complete. Copy the Lesson02 folder onto your hard drive if you haven’t already done so. As you work on this lesson, you’ll preserve the start files. If you need to restore the start files, copy them from the Adobe Photoshop CS6 Classroom in a Book DVD.
Adobe Photoshop includes a variety of tools and commands for improving the quality of a photographic image. This lesson steps you through the process of acquiring, resizing, and retouching a photo intended for a print layout. The same basic workflow applies to web images.
Strategy for retouching
How much retouching you do depends on the image you’re working on and your goals for it. For many images, you can achieve your desired outcome with just a few clicks in Adobe Camera Raw, which is installed with Adobe Photoshop. For others, you may start in Camera Raw to adjust the white point, for example, and then move on to Photoshop for more advanced retouching, such as applying filters to selected parts of an image.
Organizing an efficient sequence of tasks
Most retouching procedures follow these general steps:
- Duplicating the original image or scan; working in a copy of the image file makes it easy to recover the original later if necessary
- Ensuring that the resolution is appropriate for the way you’ll use the image
- Cropping the image to final size and orientation
- Repairing flaws in scans of damaged photographs (such as rips, dust, or stains)
- Adjusting the overall contrast or tonal range of the image
- Removing any color casts
- Adjusting the color and tone in specific parts of the image to bring out highlights, midtones, shadows, and desaturated colors
- Sharpening the overall focus of the image
Usually, you should complete these processes in the order listed. Otherwise, the results of one process may cause unintended changes to other aspects of the image, making it necessary for you to redo some of your work.
In Lesson 1, you used an adjustment layer, which gives you great flexibility to experiment with different correction settings without risking damage to the original image.
Adjusting your process for different intended uses
The retouching techniques you apply to an image depend in part on how you’ll use the image. Whether an image is intended for black-and-white publication on newsprint or for full-color online distribution affects everything from the resolution of the initial scan to the type of tonal range and color correction that the image requires. Photoshop supports the CMYK color mode for preparing an image to be printed using process colors, as well as RGB and other color modes for web and mobile authoring.
To illustrate one application of retouching techniques, this lesson takes you through the steps of correcting a photograph intended for four-color print publication.
For more information about CMYK and RGB color modes, see Lesson 14, “Producing and Printing Consistent Color.”
Resampling is changing the amount of image data as you change either the pixel dimensions or the resolution of an image.
Downsampling is decreasing the number of pixels – when you downsample, information is deleted from the image.
Upsampling is increasing the number of pixels – when you upsample, new pixels are added.
You specify an interpolation method to determine how pixels are added or deleted.
A. Downsampled B. Original C. Resampled up (selected pixels displayed for each set of images)
Keep in mind that resampling can result in poorer image quality. For example, when you resample an image to larger pixel dimensions, the image loses some detail and sharpness. Applying the Unsharp Mask filter to a resampled image can help refocus the image details.
You can avoid the need for resampling by scanning or creating the image at a sufficiently high resolution. If you want to preview the effects of changing pixel dimensions onscreen or to print proofs at different resolutions, resample a duplicate of your file.
Photoshop resamples images using an interpolation method to assign color values to any new pixels based on the color values of existing pixels. You can choose your method in the Image Size dialog box.
- Nearest Neighbor A fast but less precise method that replicates the pixels in an image. This method is for use with illustrations containing edges that are not anti-aliased, to preserve hard edges and produce a smaller file. However, this method can produce jagged effects, which become apparent when you distort or scale an image or perform multiple manipulations on a selection.
- Bilinear A method that adds pixels by averaging the color values of surrounding pixels. It produces medium-quality results.
- Bicubic A slower but more precise method based on an examination of the values of surrounding pixels. Using more complex calculations, Bicubic produces smoother tonal gradations than Nearest Neighbor or Bilinear.
- Bicubic Smoother A good method for enlarging images based on Bicubic interpolation but designed to produce smoother results.
- Bicubic Sharper A good method for reducing the size of an image based on Bicubic interpolation with enhanced sharpening. This method maintains the detail in a resampled image. If Bicubic Sharper oversharpens some areas of an image, try using Bicubic.
You can specify a default interpolation method to use whenever Photoshop resamples image data. Choose Edit > Preferences > General (Windows) or Photoshop > Preferences > General (MacOS), and then choose a method from the Image Interpolation Methods menu.