Theo Bertz: Sketchbook 03
In print and graphic design, the 1-bit bitmap TIFF remains one of the most remarkably flexible utility formats available. Containing strictly pure black and pure white pixels without gray tones, a bitmap TIFF automatically treats its white background as transparent, allowing line art, custom textures, or hand-drawn illustrations to layer cleanly over backgrounds without requiring complex vector paths or clipping masks. Furthermore, major page-layout applications like Adobe InDesign let designers instantly colorize the black artwork—and even color the transparent frame background—using standard swatches. Because 1-bit files lack heavy multi-channel color data, they can be saved at crisp, high print resolutions (such as 1,200 to 2,400 DPI) while maintaining a surprisingly small file size. This unique combination of ultra-sharp line reproduction, effortless colorization, transparent layering, and light memory footprint makes bitmap TIFFs an enduring favorite for prepress workflows, comics, and screen printing.
Theo’s original loupe sketch. Most scans arrive in RGB mode. I almost always convert to CMYL because I’m used to that mode. In CMYK mode, I can see each (CMYK) channel individually. When sharpening an image, I often apply it to each channel individual, especially the black plate where I add contrast and sometimes extra sharpening to help images pop.
When I’m making a bitmap image, I convert the image to greyscale. Sometimes, before I make that conversion, I look at the individual channels and find that one channel may work best. Of so, I view that channel and then covert it to greyscale.
Here are the default levels for that image.
I then change those levels to make the background as white as possible, and the black as clean as possible. This doesn’t always work so I sometimes use Photoshop’s dodge and burn tools to lighten or darken parts of the image.
The new “Touch Plate” channel now shows in the Channels panel.
I then sharpen the image. There are several filters to do this. I mostly use “Smart Sharpen” which seems to work best before converting the image to a bitmap.
When duplicating a channel, the default is “Black copy.” Change the name to “Touch Plate” and click OK. Note: You can rename “Black copy” to anything you’d like. Just be sure to rename it consistently on all images so that you’re only adding one new channel to your InDesign document.
The new “Touch Plate” channel now shows in the Channels panel.
Select the Levels dialog box. Go to Image > Adjustments > Levels. Here are the defaults. Note: if you’re used to working in Curves, you can accomplish roughly the same thing as when using Levels. (To access Curves, go to Image > Adjustments > Curves).
When duplicating a channel, the default is “Black copy.” Change the name to “Touch Plate” and click OK. Note: You can rename “Black copy” to anything you’d like. Just be sure to rename it consistently on all images so that you’re only adding one new channel to your InDesign document.
Here are the revised levels. Please compare to step 3. Now the black (shadows) and white (highlights) are much closer to the center (midtones) which I sometimes adjust always.
Select the Levels dialog box. Go to Image > Adjustments > Levels. Here are the defaults. Note: if you’re used to working in Curves, you can accomplish roughly the same thing as when using Levels. (To access Curves, go to Image > Adjustments > Curves).
