Resize CGImageRef without anti-liasing

Question

I am trying to resize a 10x10 pixel CGImageRef, captured like this:

CGImageRef imageRef = CGImageCreateWithImageInRect(screenShot, CGRectMake(mouseLoc.x-5, screen_height-mouseLoc.y-5, 10, 10));

CGContextRef mainViewContentContext = CGBitmapContextCreate (NULL, maskImage.size.width, maskImage.size.height, 8, maskImage.size.height*4, colorSpace, kCGImageAlphaPremultipliedFirst);

CGContextDrawImage(mainViewContentContext, NSMakeRect(0,0, maskImage.size.width, maskImage.size.height), imageRef);

Then I need to make a 250x250 pixel image like this this, but the upscaled image looks like there is anti aliasing on it (looks like this)

Roxannroxanna

Interesting question. Most of the time people are asking for the reverse. – Flexuosity

Just for people's reference and ease of Googling, what's happening here is called interpolation, not antialiasing. – Monosymmetric

Answer 1

try CGContextSetInterpolationQuality:

// disable interpolation like this:
CGContextSetInterpolationQuality(mainViewContentContext, kCGInterpolationNone);
// now draw

Conditioning

same thing :( I'm not getting perfect pixels – Roxannroxanna

@Roxannroxanna i misread your question. the example i made enforces HQ interpolation - updating... – Conditioning