Dne Ne 6. září 2009 00:05:14 Guennadi Liakhovetski napsal(a): > On Sat, 5 Sep 2009, Marek Vasut wrote: > > Dne So 5. zářà 2009 22:19:42 Guennadi Liakhovetski napsal(a): > > > On Sat, 5 Sep 2009, Marek Vasut wrote: > > > > Dne So 5. zářà 2009 10:55:55 Guennadi Liakhovetski napsal(a): > > > > > Marek, please, look in PXA270 datasheet. To support a specific > > > > > pixel format means, e.g., to be able to process it further, > > > > > according to this format's particular colour component ordering. > > > > > Process further can mean convert to another format, extract various > > > > > information from the data (statistics, etc.)... Now RGB555 looks > > > > > like (from wikipedia) > > > > > > > > > > 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00 > > > > > R4 R3 R2 R1 R0 G4 G3 G2 G1 G1 B4 B3 B2 B1 B1 -- > > > > > > > > > > (Actually, I thought bit 15 was unused, but it doesn't matter for > > > > > this discussion.) Now, imagine what happens if you swap the two > > > > > bytes. I don't think the PXA will still be able to meaningfully > > > > > process that format. > > > > > > > > Not on the pxa side, but on the camera side -- Bs and Rs swapped in > > > > the diagram above. > > > > > > And then? Are you trying to tell me, that the PXA then swaps them > > > back?... > > > > No, the software has to do it then, I'm trying to tell you that it has > > nothing to do with PXA (as PXA really doesnt care if the channel is > > actually blue or red). > > Of course it does. I asked you to swap the above two bytes, you would get > this: > > 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00 > G1 G0 B4 B3 B2 B1 B0 -- R4 R3 R2 R1 R0 G4 G3 G2 > > and PXA would still inerpret this as > > R4 R3 R2 R1 R0 G4 G3 G2 G1 G0 B4 B3 B2 B1 B0 -- > > i.e., it would take bits > > R2 R1 R0 G4 G3 > > for blue, bits > > B1 B0 -- R4 R3 > > for green, and bits > > G1 G0 B4 B3 B2 > > as red. Which, as you see, makes no sense. That's why I'm saying, that it > doesn't support this format, and we can only pass it through as raw data. Ah damn, I see what you mean. What the camera does is it swaps the RED and BLUE channel: 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00 B4 B3 B2 B1 B0 G4 G3 G2 G1 G1 R4 R3 R2 R1 R1 -- so it's more a BGR555/565 then. I had to patch fswebcam for this. Sorry for the confusion. > > Thanks > Guennadi > --- > Guennadi Liakhovetski, Ph.D. > Freelance Open-Source Software Developer > http://www.open-technology.de/ -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
