2011/8/29 Alexey Fisher <bug-tr...@fisher-privat.net> > Hallo all, > i know some people here was working with bayer raw data. I just discovered > this word for me, so i need some help to understand it correctly. > > Normal bayer based image sensor have separate pixel for each color. Usually > it made in 4 pixel squares, 1 - blue, 1 - red, 2 - green. There are > different ways to precess this data but most easiest one will get one image > pixel out of 4 physical pixels. > This also mean, if my (for example) webcam has physical sensor size of 2MP, > the real, not interpolated image data is MP*0.25. > > 1600x1200 (claimed resolution(2MP)) /2 = 800x600 (real/perfect image > resolution(0,5MP)) > > Is this correct? > > I don't think the word 'real' is useful here. If you treat pixel data as black and white data, you can see pixel size details. Of course this black and white image is polluted by the fact that for a given visible light quantity, a green pixel won't give you the same value as a blue pixel, and the resulting image will look like a mozaic.
If you take 4 pixels to make a half-sized image, you will miss some details. Not doing interpolation does not mean your image is more perfect or more real. It is just a suboptimal usage of data at your disposal. Let's suppose you could have three monochrome sensor with the same resolution as your webcam each taking the exact same image. >From this image, you can construct a subsampled image at half the resolution. With bayer data, smaller details than in the subsampled 'perfect' image are available, yet you can only have and approximation of the full resolution image. The better your interpolation, the closer you are from the 'perfect' image, for some definition of perfect. > Regards, > Alexey. > ______________________________**_________________ > Linux-uvc-devel mailing list > Linux-uvc-devel@lists.berlios.**de <Linux-uvc-devel@lists.berlios.de> > https://lists.berlios.de/**mailman/listinfo/linux-uvc-**devel<https://lists.berlios.de/mailman/listinfo/linux-uvc-devel> >
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