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POHaving trouble with Box Blur Edges
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copied!<p>I am a newbie hobbyist trying to program a box blur and I am having trouble with respect to edges. I am hoping that someone can spot the error.</p> <p>The edges are black and I am assuming that it's because the borders are not being reflected properly. I am sure this has been discussed with a fix size kernel however I am using a variable sized kernel.</p> <p>I am using the code found on another post --</p> <p><a href="https://stackoverflow.com/questions/7860575/optimized-float-blur-variations">Optimized float Blur variations</a></p> <p>However I just do not understand the reflected borders portion.</p> <p>I do not really care if optimized or not nor do I care about other kernel shapes, box shape will be just fine.</p> <p>The code is</p> <pre><code> {// code from https://stackoverflow.com/questions/7860575/optimized-float-blur-variations //-------------------------------------- int image_width ; int image_height ; int scale = 0; int weight = (radius * 2) + 1; int kernel_X = 0; int kernel_Y = 0; //-------------------------------------- float sum = 0.0; int kernel_width = radius;//set both to the same to make the kernel square int kernel_height = radius;//set both to the same to make the kernel square // HORIZONTAL for(iy = 0; iy < image_height ;iy++) { sum = 0.0; // Process entire window for first pixel (including wrap-around edge) for (kernel_X = 0; kernel_X <= kernel_width; kernel_X++) { if (kernel_X >= 0 && kernel_X < image_width) //sum += src[iy * image_width ]; sum += src[iy * image_width + kernel_X]; } //>-------------- border code does not reflect edges HELP!! // Wrap watch for left side of image & resulting black bar for (kernel_X = (image_width - kernel_width); kernel_X < image_width; kernel_X++) { // if (kernel_X >= 0 && kernel_X < image_width)// HORIZONTAL width = horizontal = X // sum += src[iy * kernel_width + image_width ];//<-------------------enter tester formula here // sum += src[iy + ix * image_width + kernel_X];//<-------------------FAIL // sum += src[iy * kernel_width + image_width ];//<-------------------streaky } // Store first window tmp[iy * image_width] = (sum / weight ); for(ix = 1; ix < image_width; ix++) { // Subtract pixel leaving window if (ix - kernel_width - 1 >= 0) sum -= src[iy * image_width + ix - kernel_width - 1]; // Add pixel entering window if (ix + kernel_width < image_width) sum += src[iy * image_width + ix + kernel_width]; else sum += src[iy * image_width + ix + kernel_width - image_width]; tmp[iy * image_width + ix] = (sum / weight);//just for testing } } // VERTICAL for(ix = 0; ix < image_width; ix++) { sum = 0.0; // Process entire window for first pixel for (kernel_Y = 0; kernel_Y <= kernel_height; kernel_Y++) { if (kernel_Y >= 0 && kernel_Y < image_height) sum += tmp[kernel_Y * image_width + ix]; } //>-------------- border code does not reflect edges HELP!! // Wrap watch for top side of image & resulting black bar for (kernel_Y = image_height-kernel_height; kernel_Y < kernel_height; kernel_Y++) { //if (kernel_Y >= 0 && kernel_Y < image_height) // sum += tmp[(iy + kernel_height - image_height) * image_width + ix]; } for(iy=1;iy< image_height ;iy++) { // Subtract pixel leaving window if (iy-kernel_height-1 >= 0) sum -= tmp[(iy - kernel_height-1) * image_width + ix]; // Add pixel entering window if (iy + kernel_height < image_height) sum += tmp[(iy + kernel_height) * image_width + ix]; else sum += tmp[(iy + kernel_height - image_height) * image_width + ix]; dst[ (scale * image_width * image_height) + (iy * image_width + ix) ] = (sum / weight); } } } </code></pre> <p>I appreciate any help on this.</p> <p>Thanks John</p> <p>edit here are some links of image examples of the edges.</p> <p>image with proper box blur <a href="http://img687.imageshack.us/img687/931/standardboxblur.jpg" rel="nofollow noreferrer">http://img687.imageshack.us/img687/931/standardboxblur.jpg</a></p> <p>Image with improper edges using the above code (notice dark bar on Top and Left edges, bottom and right are not quite right either) <a href="http://img202.imageshack.us/img202/5137/boxblurbadedges.jpg" rel="nofollow noreferrer">http://img202.imageshack.us/img202/5137/boxblurbadedges.jpg</a></p>

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