Color book design, four color printing, palette image

Color book design, four color printing, color palette from image.
Color book design, four color printing, and possibly selecting a color palette from image is part of book design for printing on offset press. But, you need to know what you are doing to achieve the best results. Color schemes can go wrong if both CMYK and RGB are not understood. RGB is made from colored light to provide a wider color array.
Selecting a color scheme
CMYK is more limited in its array. If you want the website and book colors to match, or you do not want a surprise what you see the printing on press, then follow this advice.
CMYK FOR PRINT, RGB FOR SCREENS, HTML FOR WEB
If selecting color for book printing on press and viewing an online website, select CMYK process colors first, then match RGB to CMYK. See Chapter 8 Printing on Press, for more about printing color on press.
BLACK — OR COLOR SWATCHES — WITH TINTS
Novels most often do not have any color other than black. If variation is needed on the page but color is not wanted or is not in the budget, make gray tints instead. Go to Swatches, put the cursor on [Black] to highlight, then go to the three horizontal lines in the upper right corner. Select “New Tint Swatch . . . ” and a new window opens. See “tint” at the bottom. Type in a value of 30%. Click Add. Repeat as needed but limit the number of tints to avoid a cluttered look.
MATCHING PHOTOS WITH EYEDROPPER TOOL

There is a seemingly endless number of color combinations. If you have an image that is symbolic of the subject matter of the book, select colors from the image to add to the Swatches. Limit the number of swatches to from two to five colors. An exception may be swatches for a color-coded reference book where many more may colors may be needed. If matching color from an image, always start by converting the photo or image to CMYK since that is the mode that we use when printing books on press.
To convert to CMYK in Photoshop, go to File > Convert to Profile . . . select Destination Space. Star Print Brokers uses U.S. Sheetfed Coated v2. It could also be U.S. Sheetfed Uncoated v2, but this is not a critical difference for this task. Place the photo in the document by selecting Ctrl + D and navigate to the image’s folder to select it.
While still in InDesign, use the eyedropper tool to select a color in the photo. Then go to Swatches and add the color. Repeat as needed.
Use the new swatches for select headlines, background color, or other areas where color is part of the design. The possibilities are endless. Selecting CMYK from photos is a great way to create Swatches and / or brand colors. Since RGB has the wider array, convert the CMYK color to RGB for web color. The color still might not be exact, but the chances are much greater that RGB and CMYK colors will match when selecting color using this method.