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Image convolution for QImage
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Kovid Goyal
parent
2ce3aad03e
commit
8f973eb8a7
@ -6,9 +6,16 @@
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*/
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#include "imageops.h"
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#include <stdexcept>
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#define SQUARE(x) (x)*(x)
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#define MAX(x, y) ((x) > (y)) ? (x) : (y)
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#define DISTANCE(r, g, b) (SQUARE(r - red_average) + SQUARE(g - green_average) + SQUARE(b - blue_average))
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#define M_EPSILON 1.0e-6
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#define M_SQ2PI 2.50662827463100024161235523934010416269302368164062
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#ifndef M_PI
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#define M_PI 3.14159265358979323846
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#endif
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unsigned int read_border_row(const QImage &img, const unsigned int width, const unsigned int height, int *reds, const double fuzz, const bool top) {
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unsigned int r = 0, c = 0, start = 0, delta = top ? 1 : -1, ans = 0;
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@ -38,10 +45,10 @@ unsigned int read_border_row(const QImage &img, const unsigned int width, const
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return ans;
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}
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#define ENSURE32(img) \
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#define ENSURE32(img, ret) \
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if (img.format() != QImage::Format_RGB32 && img.format() != QImage::Format_ARGB32) { \
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img = img.convertToFormat(img.hasAlphaChannel() ? QImage::Format_ARGB32 : QImage::Format_RGB32); \
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if (img.isNull()) { PyErr_NoMemory(); return NULL; } \
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if (img.isNull()) { PyErr_NoMemory(); return ret; } \
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} \
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QImage* remove_borders(const QImage &image, double fuzz) {
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@ -51,7 +58,7 @@ QImage* remove_borders(const QImage &image, double fuzz) {
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unsigned int width = img.width(), height = img.height();
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unsigned int top_border = 0, bottom_border = 0, left_border = 0, right_border = 0;
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ENSURE32(img)
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ENSURE32(img, NULL)
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buf = new int[3*(MAX(width, height)+1)];
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fuzz /= 255;
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@ -83,7 +90,7 @@ QImage* grayscale(const QImage &image) {
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QRgb *row = NULL, *pixel = NULL;
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int r = 0, gray = 0, width = img.width(), height = img.height();
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ENSURE32(img);
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ENSURE32(img, NULL);
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for (r = 0; r < height; r++) {
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row = reinterpret_cast<QRgb*>(img.scanLine(r));
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for (pixel = row; pixel < row + width; pixel++) {
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@ -94,3 +101,121 @@ QImage* grayscale(const QImage &image) {
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if (!PyErr_Occurred()) ans = new QImage(img);
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return ans;
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}
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#define CONVOLVE_ACC(weight, pixel) \
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r+=((weight))*(qRed((pixel))); g+=((weight))*(qGreen((pixel))); \
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b+=((weight))*(qBlue((pixel)));
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QImage convolve(QImage &img, int matrix_size, float *matrix) {
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int i, x, y, w, h, matrix_x, matrix_y;
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int edge = matrix_size/2;
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QRgb *dest, *src, *s, **scanblock;
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float *m, *normalize_matrix, normalize, r, g, b;
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if(!(matrix_size % 2))
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throw std::out_of_range("Convolution kernel width must be an odd number");
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w = img.width();
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h = img.height();
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if(w < 3 || h < 3) return img;
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ENSURE32(img, img);
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QImage buffer = QImage(w, h, img.format());
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scanblock = new QRgb* [matrix_size];
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normalize_matrix = new float[matrix_size*matrix_size];
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Py_BEGIN_ALLOW_THREADS;
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// create normalized matrix
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normalize = 0.0;
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for(i=0; i < matrix_size*matrix_size; ++i)
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normalize += matrix[i];
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if(std::abs(normalize) <= M_EPSILON)
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normalize = 1.0;
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normalize = 1.0/normalize;
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for(i=0; i < matrix_size*matrix_size; ++i)
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normalize_matrix[i] = normalize*matrix[i];
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// apply
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for(y=0; y < h; ++y){
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src = (QRgb *)img.scanLine(y);
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dest = (QRgb *)buffer.scanLine(y);
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// Read in scanlines to pixel neighborhood. If the scanline is outside
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// the image use the top or bottom edge.
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for(x=y-edge, i=0; x <= y+edge; ++i, ++x){
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scanblock[i] = (QRgb *)
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img.scanLine((x < 0) ? 0 : (x > h-1) ? h-1 : x);
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}
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// Now we are about to start processing scanlines. First handle the
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// part where the pixel neighborhood extends off the left edge.
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for(x=0; x-edge < 0 ; ++x){
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r = g = b = 0.0;
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m = normalize_matrix;
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for(matrix_y = 0; matrix_y < matrix_size; ++matrix_y){
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s = scanblock[matrix_y];
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matrix_x = -edge;
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while(x+matrix_x < 0){
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CONVOLVE_ACC(*m, *s);
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++matrix_x; ++m;
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}
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while(matrix_x <= edge){
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CONVOLVE_ACC(*m, *s);
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++matrix_x; ++m; ++s;
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}
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}
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r = r < 0.0 ? 0.0 : r > 255.0 ? 255.0 : r+0.5;
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g = g < 0.0 ? 0.0 : g > 255.0 ? 255.0 : g+0.5;
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b = b < 0.0 ? 0.0 : b > 255.0 ? 255.0 : b+0.5;
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*dest++ = qRgba((unsigned char)r, (unsigned char)g,
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(unsigned char)b, qAlpha(*src++));
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}
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// Okay, now process the middle part where the entire neighborhood
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// is on the image.
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for(; x+edge < w; ++x){
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m = normalize_matrix;
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r = g = b = 0.0;
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for(matrix_y = 0; matrix_y < matrix_size; ++matrix_y){
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s = scanblock[matrix_y] + (x-edge);
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for(matrix_x = -edge; matrix_x <= edge; ++matrix_x, ++m, ++s){
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CONVOLVE_ACC(*m, *s);
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}
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}
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r = r < 0.0 ? 0.0 : r > 255.0 ? 255.0 : r+0.5;
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g = g < 0.0 ? 0.0 : g > 255.0 ? 255.0 : g+0.5;
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b = b < 0.0 ? 0.0 : b > 255.0 ? 255.0 : b+0.5;
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*dest++ = qRgba((unsigned char)r, (unsigned char)g,
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(unsigned char)b, qAlpha(*src++));
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}
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// Finally process the right part where the neighborhood extends off
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// the right edge of the image
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for(; x < w; ++x){
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r = g = b = 0.0;
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m = normalize_matrix;
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for(matrix_y = 0; matrix_y < matrix_size; ++matrix_y){
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s = scanblock[matrix_y];
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s += x-edge;
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matrix_x = -edge;
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while(x+matrix_x < w){
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CONVOLVE_ACC(*m, *s);
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++matrix_x, ++m, ++s;
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}
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--s;
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while(matrix_x <= edge){
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CONVOLVE_ACC(*m, *s);
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++matrix_x, ++m;
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}
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}
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r = r < 0.0 ? 0.0 : r > 255.0 ? 255.0 : r+0.5;
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g = g < 0.0 ? 0.0 : g > 255.0 ? 255.0 : g+0.5;
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b = b < 0.0 ? 0.0 : b > 255.0 ? 255.0 : b+0.5;
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*dest++ = qRgba((unsigned char)r, (unsigned char)g,
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(unsigned char)b, qAlpha(*src++));
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}
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}
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Py_END_ALLOW_THREADS;
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delete[] scanblock;
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delete[] normalize_matrix;
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return buffer;
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}
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@ -8,7 +8,9 @@
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%ModuleCode
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#include <imageops.h>
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#define CATCH \
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} catch (std::bad_alloc &) { PyErr_NoMemory(); return NULL; \
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if (sipRes == NULL) return NULL; \
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} catch (std::out_of_range &exc) { PyErr_SetString(PyExc_ValueError, exc.what()); return NULL; \
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} catch (std::bad_alloc &) { PyErr_NoMemory(); return NULL; \
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} catch (std::exception &exc) { PyErr_SetString(PyExc_RuntimeError, exc.what()); return NULL; \
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} catch (...) { PyErr_SetString(PyExc_RuntimeError, "unknown error"); return NULL;}
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%End
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@ -17,7 +19,6 @@ QImage* remove_borders(const QImage &image, double fuzz);
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%MethodCode
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try {
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sipRes = remove_borders(*a0, a1);
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if (sipRes == NULL) return NULL;
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CATCH
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%End
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@ -25,6 +26,5 @@ QImage* grayscale(const QImage &image);
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%MethodCode
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try {
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sipRes = grayscale(*a0);
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if (sipRes == NULL) return NULL;
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CATCH
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%End
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