I made an Illustrator file with dimensions in centimeters. How do I export it to a lossless bitmap format (TIFF, ideally) with a specified size in pixels? The "Export as" option only lets me choose the resolution in pixels per inch, not per centimeter, and the other export options that do allow for specific raster size do not seem to support lossless formats.
The PPI setting does not generally mean anything in Illustrator, or even as far as raster images are concerned.
As for using pixels per centimetre, if you really must convert, then PPI/2.54=PPCM, and PPI=PPCM*2.54. Illustrator has no option to change the TIFF export dialog to PPCM.
Anyhoo, here's how to export a TIFF to specific pixel dimensions.
- Create a new Illustrator document the size you want in pixels, choose pixels as the units.
Copy and paste you graphic into that newly created document. Resize the graphic if necessary.
Export as TIFF, but do not change the PPI setting in the Export as TIFF dialog. Leave it at the default.
Note: I have noticed that some rounding can take place in Illustrator, so the exact pixel dimensions might not be available in all cases. You might be out by 1 pixel or so. If you want ultimate control on the number of pixels, use Photoshop, not Illustrator. You can place AI files as Smart Objects in Photoshop. If you want to change the PPI use the Image Size dialog in Photoshop, but make sure the resampling option is unchecked - this does not change the image, only the PPI setting.