| Adobe Photoshop Basics | |
Bitmap mode means the image consists of only pure black and pure white. A bitmap mode image is called a one-bit image and is also known as line art. (Continued below...)
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Grayscale mode means that the image contains 256 levels of gray plus black and white. Grayscale mode is also called 8-bit.
RGB stands for red, green, and blue. This image mode is a full color image. Because it uses one 8-bit channel for each color -- red, green, and blue -- it is called a 24-bit color image (8 red 8 green 8 blue = 24).
CMYK stands for Cyan, Magenta, Yellow, and Black. This color mode is used in four-color process printing, and is not usually used during the editing process.
Index mode allows you to limit the colors used in an image to specific palette. The indexed palette can have up to 256 unique colors.
The out of gamut alert is a small triangle with an exclamation mark that appears when a color is selected that will shift when the image is converted to CMYK mode.
The Web-safe alert is a small cube that appears when a color is selected that will shift or dither on systems that cannot display more than 256 colors.
Whenever the cursor appears as an eyedropper, you can click to change the foreground color.
The keyboard shortcut for the eyedropper is I.
Holding Alt/Option down when a painting tool is active temporarily changes to the eyedropper for selecting a new foreground color.
You can place up to four color samplers in your image by holding down the shift key when the eyedropper tool is selected.
Homework Assignment:
Select an image that has a pleasing range of colors. If necessary, crop the image to isolate the areas of color that are most pleasing. Convert the image to index mode. Save the Color Table (ACT) and then convert the color table to a custom swatch file (ACO) as described in Lesson3d. Post your swatch file to the forum to share with your classmates. Here's an example I created from the following image:
Click here to download the ACO Swatch Collection.
Click here to Post your Homework Now!
How to Post Attachments in the Forum
Lesson 4: Selections and Masks
