Question

I would like to upsize (explode) the image by duplicating pixels.

1 px -> 2px

Knowing how to read individal pixels (RGBA):

CFDataRef m_DataRef = CGDataProviderCopyData(CGImageGetDataProvider(myImage));  
UInt8 * m_PixelBuf = (UInt8 *) CFDataGetBytePtr(m_DataRef); 

int length = CFDataGetLength(m_DataRef); 

for (int i=0; i<length; i+=4){

    int r = i;
    int g = i+1;
    int b = i+2;
    int a = i+3;   
}

How do I go about upsizing the image. I tried copying pixels in a linear fashion but I ended up with an image of two images side by side.

Answer 1

create a CGBitmapContext at the destination size then draw the image to it.