Welcome to the MacNN Forums.

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

You are here: MacNN Forums > Software - Troubleshooting and Discussion > Developer Center > Problem converting image...

Problem converting image...
Thread Tools
Senior User
Join Date: Jun 1999
Location: San Jose, CA
Status: Offline
Reply With Quote
Jan 13, 2006, 03:23 AM
 
I am having some issues. Ever since upgrading to 10.4 (and also upgrading my copy of Xcode), the following code just gives me a jar-bled image. The code used to work fine. It would take an image that was 4 samplesPerPixel, and convert it to an image that was 1 samplesPerPixel (effectively taking a color image and converting it to black and white). I don't know if this is now easier to do with Core Image (I haven't looked at that stuff just yet), and if so I could use that (the code only needs to work on 10.4 and later systems, as the old version of my app works fine under 10.3 and earlier).

Here is my current code. If anyone spots a mistake, or a change Apple has made recently, or has suggestions on how to better do this, please let me know:

Code:
- (NSImage *)filterImage:(NSImage *)srcImage originalSize:(NSSize)originalSize {
NSAutoreleasePool *imagePool = [[NSAutoreleasePool alloc] init]; NSBitmapImageRep *TIFFRep = [NSBitmapImageRep imageRepWithData:[srcImage TIFFRepresentationUsingCompression:NSTIFFCompressionLZW factor:0.0]]; NSImage *grayImage; NSBitmapImageRep *grayRep; int samplesPerPixel = [TIFFRep samplesPerPixel]; int bytesPerSample = ([TIFFRep bitsPerPixel]/8)/samplesPerPixel; int totalBytes = [TIFFRep pixelsHigh]*[TIFFRep pixelsWide]*samplesPerPixel*bytesPerSample; unsigned char *TIFFBitmapPointer = [TIFFRep bitmapData]; unsigned char *grayBitmapPointer; grayRep = [[NSBitmapImageRep alloc] initWithBitmapDataPlanes:NULL
pixelsWide:[TIFFRep pixelsWide] pixelsHigh:[TIFFRep pixelsHigh] bitsPerSample:8 samplesPerPixel:1 hasAlpha:NO isPlanar:NO colorSpaceName:NSCalibratedWhiteColorSpace bytesPerRow:0 bitsPerPixel:0];
[grayRep setSize:[TIFFRep size]]; grayBitmapPointer = [grayRep bitmapData]; if((bytesPerSample==1)&&(samplesPerPixel>2)) {
int o = 0; int i = 0; int background = 255; for (i=0; i<totalBytes; i+=samplesPerPixel) {
int R = (int)*(TIFFBitmapPointer+i); int G = (int)*(TIFFBitmapPointer+i+1); int B = (int)*(TIFFBitmapPointer+i+2); int grayValue = (int)((R+G+B)/3); if (samplesPerPixel==4) {
int alpha = (int)*(TIFFBitmapPointer+i+3); // this is the alpha value grayValue = (int) ( (grayValue*alpha + background*(255-alpha)) / 255);
} *(grayBitmapPointer+o) = grayValue; o++;
}
} else NSLog(@"Bytes per sample != 1 or less than 3 samples per pixel");; [grayRep setSize:originalSize]; grayImage = [[NSImage alloc] initWithData:[grayRep TIFFRepresentationUsingCompression:NSTIFFCompressionLZW factor:0.0]]; [grayRep release]; [imagePool release]; return [grayImage autorelease];
}
Thanks,
Ben
     
   
Thread Tools
Forum Links
Forum Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On
Top
Privacy Policy
All times are GMT -4. The time now is 03:44 AM.
All contents of these forums © 1995-2015 MacNN. All rights reserved.
Branding + Design: www.gesamtbild.com
vBulletin v.3.8.8 © 2000-2015, Jelsoft Enterprises Ltd., Content Relevant URLs by vBSEO 3.3.2