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Originally Posted by afastrunner

Here is the code i've worked out for anyone else who would like to user it. if anyone sees any problems with the code please let me know.

I've included a few different basic image processing examples just comment/uncomment the one that you want to use. I haven't implemented any Matrix filters but will be working on that soon.

PHP Code:

    CGImageRef inImage = img.CGImage;        
    CGContextRef ctx;
    
        
        CFDataRef m_DataRef;
        m_DataRef = CGDataProviderCopyData(CGImageGetDataProvider(inImage));
        UInt8 * m_PixelBuf = (UInt8 *) CFDataGetBytePtr(m_DataRef);
    //    Byte tmpByte;
        int length = CFDataGetLength(m_DataRef);
        NSLog(@"len %d", length);
        
        NSLog(@"width=%d, height=%d", CGImageGetWidth( inImage ), CGImageGetHeight( inImage ));        
        NSLog(@"1=%d, 2=%d, 3=%d", CGImageGetBitsPerComponent(inImage), CGImageGetBitsPerPixel(inImage),CGImageGetBytesPerRow(inImage));
        

    //    int Contrast_transform[255];
    //    float contrast = .15;//quantifies the angle of the slope (in radians) of the contrast transform        
    //    for(int i=0;i<256;i++){
    //        if(i<(int)(128.0f+128.0f*tan(contrast))&&i>(int)(128.0f-128.0f*tan(contrast)))
    //            Contrast_transform[i]=(i-128)/tan(contrast)+128;
    //        else if(i>=(int)(128.0f+128.0f*tan(contrast)))
    //            Contrast_transform[i]=255;
    //        else
    //            Contrast_transform[i]=0;
    //    }    
        
        for (int index = 0; index < length; index += 4)
        {
        //    tmpByte = (m_PixelBuf[index + 1] + m_PixelBuf[index + 2] + m_PixelBuf[index + 3]) / 3;
        //    if (tmpByte >= 128)
        //        m_PixelBuf[index + 1] = m_PixelBuf[index + 2] = m_PixelBuf[index + 3] = 255;
        //    else
        //        m_PixelBuf[index + 1] = m_PixelBuf[index + 2] = m_PixelBuf[index + 3] = 0;
            
            m_PixelBuf[index + 1] = 255 - m_PixelBuf[index + 1];
            m_PixelBuf[index + 2] = 255 - m_PixelBuf[index + 2];
            m_PixelBuf[index + 3] =    255 - m_PixelBuf[index + 3];    
        
        //    m_PixelBuf[index + 1] = m_PixelBuf[index + 2] = m_PixelBuf[index + 3] = tmpByte;        
    
        //    m_PixelBuf[index + 1] = Contrast_transform[m_PixelBuf[index + 1]];
        //    m_PixelBuf[index + 2] = Contrast_transform[m_PixelBuf[index + 2]];
        //    m_PixelBuf[index + 3] = Contrast_transform[m_PixelBuf[index + 3]];
            
        }
        
    
        
        ctx = CGBitmapContextCreate(m_PixelBuf,
                                    CGImageGetWidth( inImage ),
                                    CGImageGetHeight( inImage ),
                                    8,
                                    CGImageGetBytesPerRow( inImage ),
                                    CGImageGetColorSpace( inImage ),
                                    kCGImageAlphaPremultipliedFirst );
        
        
        CGImageRef imageRef = CGBitmapContextCreateImage (ctx);
        UIImage* rawImage = [UIImage imageWithCGImage:imageRef];
        
        CGContextRelease(ctx);
        
    image.image = rawImage; 


The code seems to be malfunctioning for me (Simulator iPhone OS 2.0), everything gets either drawn to one side or not at all.



Can anyone help, I only altered the code to load an UIImage from the simulator's photo library which was called "image", so the only edited line is :

CGImageRef inImage = img.CGImage;

Anyway, this was the most helpful piece of code so far. Most of the time, the only reply you get is "buy a book"...