Thread: [libdc1394-devel] Re: dc 1394 image size & auto white balance
Capture and control API for IIDC compliant cameras
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From: Dan D. <da...@de...> - 2003-07-07 20:40:43
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On Mon, 2003-07-07 at 12:16, Tom Booster wrote: > Hi, > I'm a comp. sci. undergrad attempting to write some software > for digital cameras in C using the dc1394 library.I would > appreciate it if you could offer any assistance on how I > turn off the auto white balance feature using dc1394 > functions. Use dc1394_auto_on_off(handle, node, FEATURE_WHITE_BALANCE, 0) > I am aware of the features structure for the > library but am not sure of the functions used to toggle > features off or on. Look thru all the functions in dc1394_control.h. There is also dc1394_feature_on_off() and dc1394_set_feature_value(); > Any help would be greatly appreciated. I > would also like to know if there are smaller MONO format > sizes for images than MODE_320x240_MONO. Actually, 640x480 is the smallest MONO mode. However, it is very easy to derive a mono image from a YUV 4:2:2 image simply by copying only every other byte to a new buffer. Also, cropping from the center is very easy to do: static inline void crop(unsigned char *src, unsigned char *dest, int width, int height, double bpp) { register int i; register int stride = width*bpp; register unsigned char char *s = src, *d = dest; s += ((480 - height)/2 * 640 * bpp) + ((640 - width)/2 * bpp); for (i = 0; i < height; i++, d += stride, s += stride + (640 - width)*bpp ) memcpy( d, s, stride); } bpp is the number of bytes per pixel of the source image format. For RGB, bpp is 3, MONO is 1, and YUV 4:2:2 is 2. |