The Color Modes: Bitmap

This is the first in a series of posts discussing the color modes in Adobe Photoshop. My previous post, ‘256 Shades of Gray: A Ribald Tale of Bit Depth’ covered the color modes available in Photoshop when starting a new document. This series of postings will go into each one of those modes in a little more depth plus cover the other secondary color modes.

The Bitmap Color Mode in Adobe Photoshop

So when would using the Bitmap color mode be useful, or even necessary, in Photoshop?
What I’ve frequently used the Bitmap mode for is for a persons signature or a one color graphic or logo that needs to be included in a layout. Also when I haven’t had a high res digital file of a one color graphic, but I do have a clear and sharp print which I can scan and bring into Photoshop. And when I say “one color”, I mean one “solid” color, as a Bitmap cannot include multiple percentages.

When creating a Bitmap file you have the option of selecting a custom DPI. For Bitmaps you should not select anything lower than 1200 dpi at 100% print size. So when you place a Bitmap in an Illustrator or InDesign document it should be at 100%. If you need to scale the graphic up or in the layout, you should resize the file in Photoshop so that it resets to 100% in the layout program. You should be able to scale down without any negative effects.

And remember that anything that appears white in the Bitmap Photoshop file will appear and print transparent in the layout program.

Once in the layout program you can apply any color to the Bitmap file. If for any reason you do want to add a gradient or other effect to the Bitmap graphic you can do that in the layout program using an Opacity Mask or Effects Filters in Illustrator and Effects Filters in InDesign.

Bitmap files are pretty simple but pretty handy too...and not too limited if you consider the effects you can apply in Illustrator and InDesign.