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POCore Graphics pointillize effect on CGImage
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  1. POCore Graphics pointillize effect on CGImage
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    copied!<p>So I have been writing a lot of image processing code lately using only core graphics and i have made quite a few working filters that manipulate the colors, apply blends, blurs and stuff like that. But I'm having trouble writing a filter to apply a pointillize effect to an image like this:</p> <p><img src="https://i1130.photobucket.com/albums/m537/sagewashabaugh/PSPointillize.jpg" alt="pointillize"></p> <p>what I'm trying to do is get the color of a pixel and fill an ellipse with that color, looping through the image and doing this every few pixels here is the code:</p> <p>EDIT: here is my new code this time its just drawing a few little circles in the bottom of the image am I doing it right like you said?</p> <pre><code>-(UIImage*)applyFilterWithAmount:(double)amount { CGImageRef inImage = self.CGImage; CFDataRef m_dataRef = CGDataProviderCopyData(CGImageGetDataProvider(inImage)); UInt8* m_pixelBuf = (UInt8*)CFDataGetBytePtr(m_dataRef); int length = CFDataGetLength(m_dataRef); CGContextRef ctx = CGBitmapContextCreate(m_pixelBuf, CGImageGetWidth(inImage), CGImageGetHeight(inImage), CGImageGetBitsPerComponent(inImage), CGImageGetBytesPerRow(inImage), CGImageGetColorSpace(inImage), CGImageGetBitmapInfo(inImage)); int row = 0; int imageWidth = self.size.width; if ((row%imageWidth)==0) { row++; } int col = row%imageWidth; for (int i = 0; i&lt;length; i+=4) { //filterPointillize(m_pixelBuf, i, context); int r = i; int g = i+1; int b = i+2; int red = m_pixelBuf[r]; int green = m_pixelBuf[g]; int blue = m_pixelBuf[b]; CGContextSetRGBFillColor(ctx, red/255, green/255, blue/255, 1.0); CGContextFillEllipseInRect(ctx, CGRectMake(col, row, amount, amount)); } CGImageRef imageRef = CGBitmapContextCreateImage(ctx); CGContextRelease(ctx); UIImage* finalImage = [UIImage imageWithCGImage:imageRef]; CGImageRelease(imageRef); CFRelease(m_dataRef); return finalImage; </code></pre> <p>}</p>
 

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