How to optimize images for 65k color versions of PCD7.D4xx MB panels

FAQ #101096

 

The 65k color versions of PCD7.D4xx MB panels can display a well defined palette of RGB colors in the format rgb 565. The gif files used as images in the S-Web-Editor can contain up to 256 colors, but they are most of the time optimized according to the colors that are present in the image, which do usually not match with the colors of the PCD7.D4xx palette.

If you use unoptimized images, the panel chooses for each pixel the color that matches best, but the result can be suboptimal. This FAQ proposes a procedure that allows to improve the results using the PC based image processing software photoshop.

There are three advantages when converting the images on the PC instead of leaving the color conversion to the panel:

Suggested procedure (for panels with 65k colors, refer to FAQ 100979 for panels with 256 colors)

1. Getting the right sources
   Best results are achieved using image files with a sufficient number of colors, which means usually jpg, png, psd or tiff files.
   
2. Resize the image to the required dimensions
   Avoid making images bigger, the results are most of the time not satisfactory.
   
3. Get, install and use the free photoshop 565 filter from Telegraphics
   From www.telegraphics.com.au/sw/ you can get 5_6_5 Filter for free. Extract it, copy the filter to the filter directory of photoshop. After the next start of Photoshop you have got two new Telegraphics filters available, only the 565 is adequate for the 65k color PCD7.D4xx panels. Note for CS4 users: you need minimum version 1.3b1 of the filter (was created in June 2009), otherwise the conversion can abort with an error message.
    
4. Store the image as gif file
   Do not use Image Ready (CS, CS2) or the Store for Web... feature (CS3 +) of photoshop like you would usually do to create images for the web! These wizards suggest per default other color palettes and it is easy to make errors that make you loose the improvements of this procedure. Use Save As with file type gif instead.
   
5. Use the images in your S-Web-Editor project
   Same procedure as usual.