Re: Creating a color image with NSBitmapImageRep and greyscale data
Re: Creating a color image with NSBitmapImageRep and greyscale data
- Subject: Re: Creating a color image with NSBitmapImageRep and greyscale data
- From: Jason Horn <email@hidden>
- Date: Tue, 27 Nov 2007 23:07:54 -0500
Thanks Dave,
I was aware that the code I gave will still give a grey image. The
problem is that the image is also munged somehow. the resulting image
was actually a mosaic of three separate grey images within the borders
of the main image,with the rest of the space being black. Also, the
reason that I was attempting this was in hopes that, even though
technically still grey, CIColorMap would treat the image differently,
and yield a color image.
On Nov 27, 2007, at 10:55 PM, David Spooner wrote:
Sorry, I meant to also say that an alternative to this quick and
dirty approach is to consider the input greyscale value as the hue
component of an HSB (or related) colorspace and perform a standard
conversion from HSB to RGB (using a fixed saturation and brightness).
dave
On 27-Nov-07, at 8:34 PM, David Spooner wrote:
The preceding line sets the r, g and b components uniformly for
each output pixel, so you'll always get grey. You might try
distributing each input pixel p across r, g and b along the lines
of...
int bpr = [bitmap bytesPerRow];
for (int i = 0; i < height; ++i) {
char *row = bitmapData + i * bpr;
for (int j = 0; j < width; ++j) {
uint16_t p = pixels[i * width + j];
unsigned char *rgb = row + j * 3;
rgb[0] = p & 0x3f;
rgb[1] = (p >> 6) & 0x3f;
rgb[2] = (p >> 12);
}
}
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