Hi Terry, > However, I think it has too many grey levels because I get a very > washed out picture with the odd line on it. The spec says 16 bit, but > I think they mean 16 levels (needless to say the device came from > China).
You originally wrote: > The supplied image has the following properties (as provided by The Gimp: > > Size in Pixels: 128 x 128 > Color space: Indexed color (16 colors) > Precision: 8-bit gamma integer > File Type: Windows BMP image So they've supplied an image with a colour palette of sixteen colours where each pixel is an index into that palette from the interval [0, 16) which takes four bits to represent. This suggests the device is 16 colours. Whether the palette is fixed, e.g. TTL-level RGB plus ‘dim’, or able to be set is unknown. > My image has these properties (I've tweaked it in The Gimp to get as close a > match as possible: > > Size in Pixels: 128 x 95 > Color space: Grayscale > Precision: 8-bit gamma integer > File Type: Windows BMP image Your gray image is using eight bits to represent a level of grey in the interval [0, 256), from black to white. As I wrote initially, > It's taking each pair of pixels in a row, which given it's an indexed > BMP of sixteen colours are four bits each, and abutting them into a > eight-bit byte. It's only using the bottom four bits from each pixel so it's expecting them to be an index into a palette. My suggestion to use pic.convert() was matching this. Gimp should be able to convert to a 16-colour palette. -- Cheers, Ralph. -- Next meeting: Online, Jitsi, Tuesday, 2020-08-04 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
