Question

Is there a way to apply brightness to uiimages. For example I have a UIImageview and inside that i have a uiimage. I want to manipulate its brightness with a help of UISlider without using GlImageprocessing.

Please help me to solve this problem and please don’t suggest me about GlImageprocessing. I want to do it without using GlImageprocessing.

Answer 1

here is the code:-

        CGImageRef inImage = currentImage.CGImage;
        CFDataRef ref = CGDataProviderCopyData(CGImageGetDataProvider(inImage)); 
        UInt8 * buf = (UInt8 *) CFDataGetBytePtr(ref); 
        int length = CFDataGetLength(ref);
        float value2 =  (1+slider.value-0.5);
        NSLog(@"%i",value);
        for(int i=0; i<length; i+=4)
        {


            int r = i;
            int g = i+1;
            int b = i+2;

            int red = buf[r];
            int green = buf[g];
            int blue = buf[b];


            buf[r] = SAFECOLOR(red*value2);
            buf[g] = SAFECOLOR(green*value2);
            buf[b] = SAFECOLOR(blue*value2);
        }

        CGContextRef ctx = CGBitmapContextCreate(buf,
                                                 CGImageGetWidth(inImage), 
                                                 CGImageGetHeight(inImage), 
                                                 CGImageGetBitsPerComponent(inImage),
                                                 CGImageGetBytesPerRow(inImage), 
                                                 CGImageGetColorSpace(inImage),
                                                 CGImageGetAlphaInfo(inImage));

        CGImageRef img = CGBitmapContextCreateImage(ctx);

        [photoEditView setImage:[UIImage imageWithCGImage:img]];
        CFRelease(ref);
        CGContextRelease(ctx);
        CGImageRelease(img);

define this at the top:-

      #define SAFECOLOR(color) MIN(255,MAX(0,color))