| # Tools |
| |
| ## NxWidgets `bitmap_converter.py` |
| |
| This script converts from any image type supported by Python imaging library to |
| the RLE-encoded format used by NxWidgets. |
| |
| RLE (Run Length Encoding) is a very simply encoding that compress quite well |
| with certain kinds of images: Images that that have many pixels of the same |
| color adjacent on a row (like simple graphics). It does not work well with |
| photographic images. |
| |
| But even simple graphics may not encode compactly if, for example, they have |
| been resized. Resizing an image can create hundreds of unique colors that may |
| differ by only a bit or two in the RGB representation. This _color smear_ is the |
| result of pixel interpolation (and might be eliminated if your graphics software |
| supports resizing via pixel replication instead of interpolation). |
| |
| When a simple graphics image does not encode well, the symptom is that the |
| resulting RLE data structures are quite large. The palette structure, in |
| particular, may have hundreds of colors in it. There is a way to fix the graphic |
| image in this case. Here is what I do (in fact, I do this on all images prior to |
| conversion just to be certain): |
| |
| - Open the original image in GIMP. |
| - Select the option to select the number of colors in the image. |
| - Pick the smallest number of colors that will represent the image faithfully. |
| For most simple graphic images this might be as few as 6 or 8 colors. |
| - Save the image as PNG or other lossless format (NOT jpeg). |
| - Then generate the image. |
