I then tried Gimp and was disappointed with the results. I searched the App Store for an app that would dither and export to BMP. HyperDither was mentioned here before and I gave it a whirl. I eventually had this as part of my workflow before entering Photoshop for the final conversion. Still, I found the lack of a true BMP export to be puzzling and too cumbersome.
Enter Retro Dither. I contacted the developer and made some suggestions. He responded and was very positive with my feedback and requests. I am proud to say that there is an app on the App Store that will now export an image to BMP format! Not only that, it will allow you to chose a DPI setting when exporting. Most conversion apps default to 72 PPI and do not have anyway to adjust this. Retro Dither does.
I would encourage anyone using a Mac to give it a shot. I find it does an excellent job.
- You will need to crop and size your image to 400x240 @ 70 PPI before dragging into Retro Dither. This may be resolved in the near future. Maybe not. An easy enough task to do regardless.
- Don't forget to set the PPI to 70 when you export the file.