On Jul 25, 9:53 pm, beertje <[EMAIL PROTECTED]> wrote: > This has me a bit stumped... > > I'm trying to extract pictures from a file. So far I'm successfully > retrieved the header and what I think is the colour for each pixel. > Here's the description: > > """ > 3) The picture data format: > The color information is 15 bit data stored in 16 bit. This means the > most > significant bit is unused. The data is stored line for line in little > endian Intel format starting with top left edge to bottom right edge. > This > is normally called chunky format. > > Bit 0.. 4 blue value > Bit 5.. 9 green value > Bit 10..14 red value > """
Do yourself a favour -- read the next line in TFM. It says: "To get 8 bit RGB data, all these values must be shifted 3 bits to the left." > > So I've got a list of 16-bit numbers, but how to extract RGB info from > those I'm a bit lost. I thought at first I should convert the decimal > (say 23294) into a binary (say 0101101011111110) into something like > this: > blue: 01011 > green: 01011 > red: 11111 I think you've lost it somewhere; 23294 -> red 22, green 23, blue 30; see below. > > But encountered two problems: First, I don't know what the best way is > to do this conversion, b = rgb & 31 g = (rgb >> 5) & 31 r = (rgb >> 10) & 31 IOW like you would in C; IOW isn't this whole question OT? > but more importantly I don't see how every > colour could possibly be represented like this. 65535 is presumably > white, but converting this into chunks of 5 gives me a 31, 31, 31, a > dark shade of grey. It is a dark shade of grey in 8-bit RGB, but it's as white as the driven snow in 5-bit RGB. You need to scale it up. TFM indicates rgb8 = rgb5 << 3 -- i.e. multiply by 8, but 31 * 8 is 248, not 255. You might want to try rgb8 = (rgb5 * 255 + 16) / 31 instead. > > I guess I'm on the wrong track completely? > > I'm a bit unsure about how to treat what the guide calls 'UWORD'... TFM says "UWORD is unsigned 16 bit", so you treat it as an Unsigned (16-bit) WORD, which is what you [should] have been doing. > > Here's the full > guide:http://lists.kde.org/?l=kde-games-devel&m=105548792026813&w=1#2 > (16-bit PC cards) -- http://mail.python.org/mailman/listinfo/python-list
