Re: NSImage and 8 bit

FROM : Robert W. Kuhn
DATE : Tue Nov 30 09:26:16 2004

On 29.11.2004 20:13 Uhr +0000 Marcel Weiher wrote:

> Try using NSBitmapImageRep directly, the code you are using may or may
> not do what you're thinking.


Thank you for your help. I discovered that I have to use
initWithBitmapDataPlanes:
        pixelsWide:
        pixelsHigh:
        bitsPerSample:
        samplesPerPixel:
        hasAlpha:
        isPlanar:
        colorSpaceName:
        bytesPerRow:
        bitsPerPixel:


My code now looks like that:

mLeftImg  = [NSImage alloc];
[mLeftImg setDataRetained:YES];
[mLeftImg
initWithContentsOfFile:@"/Users/rkuhn/Programmierung/Disparity/A_000_000.bmp"];
NSLog(@"BPP: %i", [mLeftImg bitsPerPixel]);

NSBitmapImageRep *bmpRep;
NSData *dat;
dat = [NSData dataWithContentsOfFile:
@"/Users/rkuhn/Programmierung/Disparity/A_000_000.bmp" ];
bmpRep = [[NSBitmapImageRep alloc] initWithBitmapDataPlanes:(unsigned
char **)&dat
           pixelsWide:[mLeftImg width]
   pixelsHigh:[mLeftImg height]
   bitsPerSample:8
   samplesPerPixel:1
   hasAlpha:NO
   isPlanar:NO
   colorSpaceName:NSDeviceWhiteColorSpace
   bytesPerRow:[mLeftImg width]*1//pixelsWide*samplesPerPixel
   bitsPerPixel:8//bitsPerSample*samplesPerPixel];
       
NSLog(@"BPP: %i", [bmpRep bitsPerPixel]);


The Log:
2004-11-30 09:22:32.383 Disparity[1513] BPP: 32
2004-11-30 09:22:32.390 Disparity[1513] BPP: 8

Ugly code. Not very handy to load first the image (to get width and
height)
and the the data again.


> This is probably a cached representation, so you are getting the depth
> of the bitmap cache.  The last time I checked NSImage discards the
> original data unless you tell it to -setDataRetained:YES.


I also did try this. I always get only 32bit-Data. Also the NSImage has
always only one NSBitmaprepresentation - the 32bit data.


Mit freundlichen Grüßen
Robert W. Kuhn