Re: Creating black and white image
Re: Creating black and white image
- Subject: Re: Creating black and white image
- From: Osamu Shigematsu <email@hidden>
- Date: Thu, 23 Dec 2004 04:57:25 +0900
Thank you very much for your information.
I read NSImage_monochrom.m, but this sample computes color of all
pixels.
With QuickTime, converting color depth (dithering), resizing (affine
transform) are done in single function call.
I hope NSImage's -compositeToPoint:operation:fraction: does that work,
but converting depth does not work well.
I added following lines at the end of my bitmap creating function, and
checked the output. The image size (dpi) was changed, but it was color
image. The image (dst) has only one Image Representations, or 1 bit
depth NSBitmapImageRep.
NSData *tiff = [dst TIFFRepresentation];
[tiff writeToFile:[@"~/Desktop/test.tif"
stringByExpandingTildeInPath] atomically:NO];
Anyway, the performance of NSReadPixel may not good, and the code of
NSImage_monochrom.m is too long for it's feature. I will try to create
NSBitmapImageRep from QuickDraw's PixMapHandle.
This might be not so cool, but code will be simple.
On Dec 23, 2004, at 4:09 AM, Ricky Sharp wrote:
Check out the following example:
<http://developer.apple.com/samplecode/Monochrome_Image/
Monochrome_Image.html>
Specifically, look at the NSImage_monochrom.m file.
Note that the code uses NSReadPixel which is quite slow. I've since
optimized a local copy of it by directly accessing the pixels. I hope
to one day submit this code. Currently, it doesn't yet support bitmap
reps that contains alpha or is planar.
--
Osamu Shigematsu
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