Photoshop Masking & Compositing, by Katrin Eismann
Chapter 1, The Creative Process and Configuring Photoshop

This book is considered by many to be one of the classics for teaching how to build selections or masks in Photoshop. Katrin divides the book into four main sections: selections, masks, selecting to preserve fine detail (like hair) and compositing (putting multiple images together).

The first section consists of four chapters that are about configuring photoshop and making selections. In this particular writeup, we will summarize Chapter 1, The Creative Process and Configuring Photoshop.

This first chapter one covers two main things. First, it’s an introduction to composites and some of the artisitic possibilities made possible by composites. Second, it’s a recommendation for how to initially configure all your Photoshop preferences. I’ll leave the first part for you to read yourself in the book. What we’re going to cover here is how Katrin recommends you initially set up your Photoshop preferences. Even though I’ve been using Photoshop and it’s cousin Photoshop Elements for many years, I still found useful information in the review of all the preferences and decided to change a few of mine after reading this.

Some of this chapter is a bit mechanical as she goes through most of the preference settings possible in Photoshop. The book appears to be written for Photoshop CS. The preferences in CS2 are nearly identical so the book is useful for either Photoshop version. If you have CS2, you may notice a few screen shots that are a little different than what the book shows.

I tried to make it so you can just page through this summary and stop when you see a screen shot of an interesting preference screen or you can check out the settings that I found particularly interested even though I’ve been using Photoshop for a little while:

• Image Interpolation. How the default image interpolation setting works and how to override it in normal Photoshop use
• History log. I didn’t even know about the history log feature.
• .PSB file format. What is this format and what does the preference control?
• Maximize PSD file compatibility. What does this really do?
• Default Color Settings. How to understand and set the default color settings in Photoshop.
• Configuring Profile Mismatch Warnings. How to configure the warnings for profile mismatches and what they mean.

Here are the preferences that she covers:

General Photoshop Preferences




Image Interpolation. Interpolation is the process for changing the resolution of a photo and it can be either upsizing (making more pixels) or downsizing (reducing the number of pixels). Different techniques can be used for interpolation and this preference controls which technique Photoshop will use by default when you upsize or downsize. Katrin recommends Bicubic Smoother for upsizing and Bicubic Sharper for downsizing. After setting these preferences, these will be the default options in Photoshop For some operations like the Image Size command, you can still override these in the dialog, but for others like Free Transform, there is no dialog to control them so the default is always what is used.

Since I rarely upsize images and frequently downsize images (for web display or to send in email), I set this default to Bicubic Sharper.

History States. You can think of this preference like the number of undo states that Photoshop will remember. The advantage of having a higher number here is that Photoshop will remember more undo states. The disadvantage is that each undo state requires memory (bigger changes take more memory) and each open document has it’s own set of history states. While 20 undo states might sound like quite a bit, it depends upon the type of operation. It is a lot of states if what you are doing is creating adjustment layers, but it is not a lot if you are painting on a mask or cloning. Each brush stroke takes a separate undo state and 20 can get used up very quickly.

In my own personal opinion, if you use Adobe Bridge and Photoshop CS2 and have less than 1GB of RAM, you probably don’t want to set this number higher because with both of those programs running and a few open images, you will start to become RAM challenged which will cause disk swapping which can really slow Photoshop down. At 1GB of RAM, I set this to 30 to give me a few more bursh strokes in the undo stack. If you have above 1GB of RAM, you could even set this higher.

Export Clipboard. If you don’t have a lot of memory (<1GB) and you don’t copy/paste much between Photoshop and other applications, you probably want this setting turned off because that enables Photoshop to use a much more memory efficient mechanism for cut/copy/paste clipboard handling. If you turn this setting on, the Photoshop will put an entire copy of whatever you have copy or cut to the clipboard onto the Windows system clipboard. This has the advantage of making the clipboard more interoperable with other applications that you might want to copy/paste with, but it has the disadvantage that Photoshop can’t use it’s internally efficient clipboard mechaism and must use the less efficient Windows mechanism.

If you do have plenty of memory (>1GB), you probably want to turn this on to enable better clipboard interoperability with other applications.

History Log. This is a feature that was introduced in Photoshop CS and it’s one I didn’t know existed until I read this book. Turning this on, tells Photoshop to keep a log of every change you make to an image and store it in the image’s metadata, a separate text file or both. You can further control how much detail is recorded by specifying one of the following:

• Sessions Only – just records when you open and close a file
• Concise – Keeps a record of every step you perform, similar to what you see in the history palette
• Detailed – Surprisingly detailed record of everything you do, similar to what you see in the actions palette (includes detailed dialog settings, etc…).

File Handling




Image Previews. This controls whether image previews are saved with your files. This is not the same option as Adobe Bridge has for saving image thumbnails in a cache. To tell you the truth, I still don’t quite understand what this option really does or know what we should really set it at and Katrin doesn’t explain much more than this.

Ignore EXIF sRGB tag. This option tells Photoshop to ignore an sRGB color profile tag embmeeded in an image. Normally you would not want to do this, but apparently this preference was added to deal with some cameras that were tagging images as sRGB even when the camera was set to aRGB and the image was actually aRGB. So, you would only need this preference if you purposely set your camera to aRGB and found that it was tagging the images as sRGB. I suspect this is not needed with most modern cameras and you will not need this option if you shoot in sRGB.

Ask before saving layered TIFF files. This option is here because some other programs or printers have historically had problems with TIFF files containing layers. Apparently this problem is not as common as it used to be and many systems that use TIFF files now support layers. You would only want to turn this on if you think you need a reminder before saving a TIFF file with layers.

Enable large document format (.psb). The PSD file format is limited to 30,000 pixels. If you want to save a file larger than that, you can save it as either the new PSB format (up to 90 billion pixels) or as a TIFF file (up to 4GB). The PSB files are not backward compatible with older version of Photoshop. If you don’t anticipate making files larger than 30,000 pixels, it doesn’t matter what you set this to. If you might make files that large without intending to and don’t want Photoshop to let you save files that won’t be compatible with older versions of Photoshop then don’t enable this preference. Otherwise, don’t worry about it.

Maximize PSD file compatibility. This preference controls whether Photoshop saves (in your PSD file) an extra composite layer that contains a merged copy of what your finished image looks like (e.g. what you would see on screen or print). The problem with this option is that this extra layer takes space and makes your PSD files noticably larger (as much as 33% larger). The main reason to use this option is for compatibility with 3rd party applications that read PSD files, but don’t know how to process all the layers in them. Those applications will often look for this merged composite layer to use that as what they render when showing you the PSD file. Katrin recommends that if you don’t know that you need this on, then turn it off to save disk space in your files. If you run into some non-Photoshop application that is having trouble displaying or operating on your PSD files, you can always come back and turn it on and resave the offending files.

Display and Cursors




Color channels in color. This option controls whether color channels are display in color or black and white. Katrin recommends that you leave color channels in grayscale because it’s harder to see the detail in color than grayscale.

Painting cursors. Katrin recommends setting your cursor preference to Brush Size because this lets you see the size of the brush you are painting with. She points out that you can always temporarily switch to a precision cursor by pressing the capslock key when painting.

Transparency and Gamut




Transparency Settings: Grid Size & Colors. This setting controls how transparent pixels are represented. Katrain recommends just leaving this at it’s default setting.

Gamut Warning. When you have any out of gamut warning enabled for your image (such as the option in the View menu), this preference controls how the out-of-gamut is displayed. The default is a battleship gray. Katrin suggests that gray works for some images, but some people may want to change it to a color that is less likely to occur in nature such as a lime green or magenta.

Units and Rulers




Units. This controls what units are used in rulers. Pick what you want. A tip that Katrin shares is that you can double click in the rulers and it will bring up the preference dialog to change the units temporarily.

Column Size. This controls column sizes if you are doing work for newspapers or magazines.

Plug-ins and Scratch Disks





Scratch Disks. This tells Photoshop which disks to use for extra space when Photoshop runs out of RAM memory. Katrin recommends picking your fastest drive for your scratch disk. I’ve heard other people recommend that, if you have multiple fast hard disks, you should put the Photoshop scratch disk on a different drive from your OS swap file and from the disk that you normally save your Photoshop files to.

Memory and Image Cache




Cache Settings. The image cache helps improve your screen update speed by maintaining several different sizes of your image in RAM at different zoom levels. When you make a change to your image, Photoshop can make the change to the cached copy at your current zoom level first and update the screen fairly quickly. This setting controls how many different sizes Photoshop caches for this purpose. The default is 4. If you have a lot of RAM, you may want to increase it to 6.

Use Cache for Histogram in Levels. Katrin strongly recommends turning this preference off. It’s purpose is to speed the rendering of histograms when you are working on your image at views other than 100%. She reasons that if you need to look at the histogram, you need it to be accurate, not based on a cached smaller version of your image. For some reason, I don’t see this preference in my copy of CS2. I wonder if it’s no longer in Photoshop or has moved somewhere else.

Memory Usage. This controls how much of your total available RAM Photoshop is allowed to use. There appear to be a lot of different theories on how to best set this as I’ve read a number of them in various internet articles. Katrin recommends setting this to 90 percent of available RAM. If you are running other programs at the same time as Photoshop, you will probably need to set this significantly below 90 percent. I’ve personally found that Adobe Bridge takes a significant amount of memory (particularly if you are using ACR for RAW files) so you need to make sure there’s enough memory available for Bridge.

[[Due to length limits on a single posting, this is continued in the next posting in the thread]]

[[Continued from previous posting]]


Color Settings



A color working space is a mapping between a given numeric color value and an actual display or rendering color. Examples of color spaces are sRGB, AdobeRGB, LAB, ProPhotoRGB. A large working space (such as ProPhotoRGB) can express lots of different colors (even more than are found in nature), but the colors within the color space are further apart. A smaller working space (such as sRGB) cannot express as many colors, but the colors it can express are closer together potentially making for finer color gradations.

A color managed application (like Photoshop) is one that supports working spaces and can properly render and manipulate an image from any of it’s supported working spaces. A non-color managed application is one that is hardwired to a particular working space (usually sRGB) and typically doesn’t even recognize what working space a file is in or support other working spaces. Most internet browsers are examples of non-color managed applications. They are usually “hardwired” to assume an image is in sRGB even if it’s labelled with a different color space. That’s why images that are posted on the internet usually need to be in sRGB in order to display proper color.

AdobeRGB is a popular color space for advanced digital photographers because it can capture a few more colors than sRGB can, but it’s not so wide a color space that it requires 16-bit images. A common mistake is for a photographer to take photos in AdobeRGB and them post them on the internet without first converting them to sRGB. If this is done, the images will often looks washed out when viewed in a non-color-managed browser.

Configuring the Color Settings

The color settings dialog box is in the Edit menu and labelled “Color Settings”.

Katrin says that if you have never set anything in this dialog, then you do not have the best defaults for photography work in Photoshop. It’s not disastrous, but it can be better. According to her, a quick way to set Photoshop up better for photography is to choose “North America Prepress 2” from the settings drop-down in this dialog.

RGB Working Space

In the working spaces section of this dialog, you get a chance to control how Photoshop behaves when you pick RGB or CMYK. For RGB, you can pick from a whole bunch of different types of RGB working spaces including sRGB, AdobeRGB, ColorMatchRGB, AppleRGB, ProPhotoRGB, WideGamutRGB, CIE RGB, etc…


Katrin recommends selecting AdobeRGB for photography because it has a wider color gamut than sRGB and because it contains nearly all of the colors found in popular CMYK printer gamuts. She points out that you do have to be careful because AdobeRGB contains some colors (particularly bright greens) that are often not printable and if you end up with those in your image, it will not print like you see it on your screen. I won’t argue against Katrin’s AdobeRGB recommendation if you fully understand color spaces and how to best use them, understand printer profiles and soft proofing for printing and if you know when you need to convert to sRGB for web display or other purposes. But, if you aren’t well versed in color spaces yet, it’s a lot easier to goof up when not using sRGB.

CMYK Working Space

You only need to worry about what this is set to if your images will be reproduced on a commercial printing press that requires a CMYK formatted image. Desktop inkjet printers and most online photo printing services do not take CMYK images – they take sRGB images and their own software converts the images to the different ink colors in the printer which are often CMYK.

Katrin says that most of what you need to really do CMYK prepress preparation in Photoshop is being the scope of this book. She recommends the book – Real World Adobe Photoshop CS by David Blatner and Bruce Fraser as a reference for anyone who needs to use Photoshop with CMYK. I can also recommend Dan Margulis’ book Professional Photoshop as another CMYK reference if you need it.

Color Management Policies

The color management policies section of this dialog tells Photoshop what it’s supposed to do if it encounters an image that has no embedded color profile or if it encounters one that is different than your default. There are three different choices for each type of color:

• Convert to Working RGB. If you open a file in Photoshop that has a different RGB profile than your default, this setting tells Photoshop to convert the image to your default profile. Katrin only recommends using this setting if you have a pretty closed-loop environment and you know a lot about the source of your images and your default is set to a wide working space like AdobeRGB.
• Preserve Embedded Profiles. This tells Photoshop to honor the profile that is embedded in the image and not change it. This seems like the safest setting to me because you can see the image with it’s embedded profile and then decide if you need to convert or assign a different profile..
• Off. This tells Photoshop to ignore the embedded profile and assign your default working space to the image. This is almost never a good idea.

The three checkboxes control whether Photoshop should ask you before applying a change in profile according to the above settings. Katrin recommends leaving the two checkboxes about asking when opening checked, but says you can safely turn the pasting option off since you nearly always want the clipboard data to be converted to the target color space when pasting.

Dealing with Profile Warnings

Katrin says that one of the most common questions she gets from her students is what to do with the profile warning dialogs that come up when you open an image with a missing or mismatched color profile.

The warning about a mismatched profile just means that you are opening an image that doesn’t match your default working space. For example, if you default working space is sRGB and you open an AdobeRGB image, you can get this warning. When you get this warning, you have three choices:

• Use the embedded profile. This opens the image in the working space that the image is labelled with and ignores your default working space. So, if your default working space is sRGB and you open an AdobeRGB image and select this option, Photoshop will keep the image in AdobeRGB.
• Convert document’s colors to the working sapce. This option converts the document from it’s embedded working space to your default working space. So, if your default working space is sRGB and you open an AdobeRGB image and select this option, Photoshop will convert the image from AdobeRGB to sRGB and embed the sRGB profile in it.
• Discard the embedded profile. This option ignores the embedded profile and assigns (not converts) the default working space to the image. So, if your default working space is sRGB and you open an AdobeRGB image and select this option, Photoshop will assign the sRGB profile to the image. Assigning a profile just changes it’s label and does not change any of the color numbers in the file. The only time you should choose this is if you know the profile embedded in the image is wrong. If you choose this option and the embedded profile is not wrong, you will likely damage the color of your image.

The warning about a missing profile is telling you that the image you opened has no embedded profile. You are again given three choices:

• Leave as is. This tells Photoshop to assign the default working space to it and use that to display and minipulate it in Photoshop, but don’t embed a profile in it when saving.
• Assign Working RGB. This is essentially the same as the first option, but it will embed the default working space in the file when saving. You would use this optoin if you know the untagged file is the same as your default working space.
• Assign Profile. This lets you pick which profile you’d like to assign to the file. You would use this option if you know which profile this file is supposed to be in. For example, if your default working space is AdobeRGB and you open an image from the web that is probably sRGB, but doesn’t have an embedded profile (many web images do not), you could pick sRGB here.

[FONT=Times New Roman]Hello John,[/FONT]

[FONT=Times New Roman]In your review of Chapter 1, which I found very readable and interesting, I would like to comment further on the screen resolution setting under Preferences and the Preferences setting for image preview.[/FONT]
[FONT=Times New Roman]I provided the information on screen resolution to a question on another thread but thought that this reading group might find it of interest too. I regret that I do not recall the source of the following article. [/FONT]
[FONT=Times New Roman]On my main monitor (ViewSonic G220fb set at 1280 x 1024 and using a 256MB DDR ATI Radeon 9800XT video card) I found that to make my rulers accurate in Photoshop CS2, I had to set my screen resolution to 84 instead of the default 72.[/FONT]

[FONT=Times New Roman]The article which deals with this screen resolution setting follows:[/FONT]

[FONT=Times New Roman]Grab a ruler (a real ruler) and open any image in PS. Make sure rulers are turned on in PS (view - rulers), choose view - print size and then view - show rulers. Now hold your real ruler up to the screen and you will see that the ruler on the screen and the one in your hand don't match.[/FONT]
[FONT=Times New Roman]The 2 rulers don't match because PS makes an assumption that all screens are 72 ppi which is not true today.[/FONT]
[FONT=Times New Roman]Start by choosing file - new. Set the width to 1 inch and the resolution to 72 ppi (the height and other settings don't matter in this case) and click OK. Next choose view - actual pixels and make sure your PS rulers are visible (view rulers).[/FONT]
[FONT=Times New Roman]To determine the actual resolution of your display hold the physical ruler up to your screen and adjust the percentage setting shown in the lower left of the document window until the on screen ruler matches the real one. To adjust the percentage, just click on it, type in a new value and then press shift/enter. Shift/enter keeps the percentage highlighted so that you can quickly change the setting multiple times. Once the two rulers match, grab a calculator and multiply the new number by 72 (in my case it is 116% so that would be 72 x 1.16 = 83.52). The number you get is the precise resolution of your specific screen in pixels/inch (every screen will have a different resolution, even if the model and brand are identical)[/FONT]
[FONT=Times New Roman]To check it out create a new document that’s 1" wide and has the same resolution as your screen. Next choose view-actual pixels and measure it onscreen with a physical ruler. If its not 1 inch then calculate your screen resolution again..[/FONT]
[FONT=Times New Roman]Now let’s use PS to display all our documents correctly in print size view. Choose - edit - preferences – units & rulers, set the screen resolution setting to what was calculated above and click OK. Now open any image and choose view-print size to see if it is accurate. Compare the onscreen ruler to your physical ruler and ....wait a minute, it hasn't improved. But with the same document open, click on the zoom tool in the toolbox and click on the print size button that appears in the options bar. That should cause your image to display correctly.[/FONT]
[FONT=Times New Roman]There are actually 2 print size commands in PS. They should work the same but they don't. The one in the view menu always assumes that your screen resolution is 72 ppi while the zoom tool's option bar uses the screen resolution setting in preferences to determine the true resolution of your screen - therefore displaying images accurately.[/FONT]
[FONT=Times New Roman]So once everything is set up correctly, just ignore the view-print size command and instead use the zoom print size button.[/FONT]


[FONT=Times New Roman]In your remarks concerning IMAGE PREVIEW:[/FONT]

[FONT=Times New Roman](Image Previews. This controls whether image previews are saved with your files. This is not the same option as Adobe Bridge has for saving image thumbnails in a cache. To tell you the truth, I still don’t quite understand what this option really does or know what we should really set it at and Katrin doesn’t explain much more than this.)[/FONT]

[FONT=Times New Roman]I have rarely found any information on this particular preference setting. The information I did find was in Photoshop Color Correction – by Michael Kieran.[/FONT]
[FONT=Times New Roman]“In the Saving Files Preference area, this option lets you specify whether to save a thumbnail of each image as the file icon. Some people love seeing their files as little pictures, and others resent the extra time it takes to display them. It’s up to you.”[/FONT]
[FONT=Times New Roman]Personally I find it redundant and a waste of time, however others may find it useful as Mr. Kieran points out.[/FONT]

Originally Posted by jfriend Katrin recommends selecting AdobeRGB for photography

All well and good - but if you are going to display on the web, and/or print via EZPrints and SmugMug - you must convert to sRGB.

Originally Posted by Andy All well and good - but if you are going to display on the web, and/or print via EZPrints and SmugMug - you must convert to sRGB.

I agree - smugmug printing (as do nearly all online printing services) needs sRGB for best printed results.

To add to that, my sentence that follows in the writeup says: "I won’t argue against Katrin’s AdobeRGB recommendation if you fully understand color spaces and how to best use them, understand printer profiles and soft proofing for printing and if you know when you need to convert to sRGB for web display or other purposes. But, if you aren’t well versed in color spaces yet, it’s a lot easier to goof up when not using sRGB."

John, I set up my PSCS2 according to the settings rec'd by the author that you reviewed above. I changed my unit settings from inches to pixels.

I am not sure I like that as well, as when I crop things, now I ahve to think in terms of pixels not image sizes in inches at 300 PPI or so.

It was simpler for me to just chose a 4 x 5 aspect ratio, or an 8x10 ratio, or a 8 x 24 ratio for a panorama.

If I try to do that with 4x5 pixels, I end up with a mere tiny fraction of the image, not the entire image.

AM I misunderstanding something here?? Or will I love to learn to measure images in pixels, and think in pixels?

Originally Posted by pathfinder John, I set up my PSCS2 according to the settings rec'd by the author that you reviewed above. I changed my unit settings from inches to pixels. I am not sure I like that as well, as when I crop things, now I ahve to think in terms of pixels not image sizes in inches at 300 PPI or so. It was simpler for me to just chose a 4 x 5 aspect ratio, or an 8x10 ratio, or a 8 x 24 ratio for a panorama. If I try to do that with 4x5 pixels, I end up with a mere tiny fraction of the image, not the entire image. AM I misunderstanding something here?? Or will I love to learn to measure images in pixels, and think in pixels?

Whether to work in pixels or inches is surely a personal preference thing and depends upon not only your preference, but also what you're trying to accomplish at the time. For cropping with the crop tool, you can specify either pixels or inches by just putting "px" or "in" at the end of the units regardless of what the preference is set to. If find that sometimes I'm trying to get an 8"x10" ratio and it's easier to work in inches and sometimes I'm trying to get an exact 640x480 pixel image and I want to work in pixels - it just depends upon the task. It's also easy to switch the units displayed in the info palette by just clicking on the "+" icon next to the X,Y and you can easily change from inches to pixels or to something else.

So, Katrin is just expressing her preference, but it's fine for you to have a different way of doing things if that feels more comfortable.

Jim I believe there were a couple parts in the book, where two images need to be exactly the same size, down to the pixel in order for certain functions to work. I'm sorry, I don't remember exactly which chapter it was that I remember reading this. But I'm pretty sure that was one of the reasons for measuring in pixels instead of Inches.

I understand that Nick.

And I know that I can type in inches or px or whatever, John. But that is an extra step...

I guess that my photo editing is much more likely to involve cropping to a certain size or ratio, than editing and compositing images to match at the pixel level. I can understand that the author may have exactly the opposite requirements.

I'll quit whining now