How to get the pixel color values of custom image inside imageview ios?

Question

I know similar question have been asked before. What I want is to get the RGB pixel value of the Image Inside the `Imageview`, so it can be any image that pixel values we want to get. This is what I have used to get the point where the image is clicked. ``` - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; if ([touch tapCount] == 2) { //self.imageView.image = nil; return; } CGPoint lastPoint = [touch locationInView:self.imageViewGallery]; NSLog(@"%f",lastPoint.x); NSLog(@"%f",lastPoint.y); } ``` And To get the Image I have Pasted this code. ``` + (NSArray*)getRGBAsFromImage:(UIImage *)image atX:(int)xx andY:(int)yy count:(int)count { NSMutableArray *result = [NSMutableArray arrayWithCapacity:count]; /** It requires to get the image into your data buffer, so how can we get the `ImageViewImage` **/ CGImageRef imageRef = [image CGImage]; NSUInteger width = CGImageGetWidth(imageRef); NSUInteger height = CGImageGetHeight(imageRef); CGC…

Accepted Answer

Use this example article. It is talking about a color picker using images. You can understand required info very easily from it. Helped me in my app. Let me know if any help/suggestion needed ..:)

EDIT:

update your `getPixelColorAtLocation:` like this. It will give you correct color then.

```
- (UIColor*) getPixelColorAtLocation:(CGPoint)point {
    UIColor* color = nil;
    CGImageRef inImage = self.image.CGImage;
    // Create off screen bitmap context to draw the image into. Format ARGB is 4 bytes for each pixel: Alpa, Red, Green, Blue
    CGContextRef cgctx = [self createARGBBitmapContextFromImage:inImage];
    if (cgctx == NULL) { return nil; /* error */ }

size_t w = CGImageGetWidth(inImage);
    size_t h = CGImageGetHeight(inImage);
    CGRect rect = {{0,0},{w,h}};
/** Extra Added code for Resized Images ****/
    float xscale = w / self.frame.size.width;
    float yscale = h / self.frame.size.height;
    point.x = point.x * xscale;
    point.y = point.y * yscale;
 /** ****************************************/

/** Extra Code Added for Resolution ***********/
    CGFloat x = 1.0;
    if ([self.image respondsToSelector:@selector(scale)]) x = self.image.scale;
/*********************************************/
    // Draw the image to the bitmap context. Once we draw, the memory 
    // allocated for the context for rendering will then contain the 
    // raw image data in the specified color space.
    CGContextDrawImage(cgctx, rect, inImage);

// Now we can get a pointer to the image data associated with the bitmap
    // context.
    unsigned char* data = CGBitmapContextGetData (cgctx);
    if (data != NULL) {
        //offset locates the pixel in the data from x,y. 
        //4 for 4 bytes of data per pixel, w is width of one row of data.
//      int offset = 4*((w*round(point.y))+round(point.x));

int offset = 4*((w*round(point.y))+round(point.x))*x; //Replacement for Resolution
        int alpha =  data[offset];
        int red = data[offset+1]; 
        int green = data[offset+2]; 
        int blue = data[offset+3]; 
        NSLog(@"offset: %i colors: RGB A %i %i %i  %i",offset,red,green,blue,alpha);
        color = [UIColor colorWithRed:(red/255.0f) green:(green/255.0f) blue:(blue/255.0f) alpha:(alpha/255.0f)];
    }

// When finished, release the context
    CGContextRelease(cgctx); 
    // Free image data memory for the context
    if (data) { free(data); }

return color;
}
```

Let me know this fix does not work .. :)

Here is the GitHub for my code. Use it to implement picker image. Let me know if more info needed

How to get the pixel color values of custom image inside imageview ios?

Solution

Problem