/* imagediff - Compare two images * * Copyright © 2004 Richard D. Worth * * Permission to use, copy, modify, distribute, and sell this software * and its documentation for any purpose is hereby granted without * fee, provided that the above copyright notice appear in all copies * and that both that copyright notice and this permission notice * appear in supporting documentation, and that the name of Richard Worth * not be used in advertising or publicity pertaining to distribution * of the software without specific, written prior permission. * Richard Worth makes no representations about the suitability of this * software for any purpose. It is provided "as is" without express * or implied warranty. * * RICHARD WORTH DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN * NO EVENT SHALL RICHARD WORTH BE LIABLE FOR ANY SPECIAL, INDIRECT OR * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS * OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. * * Author: Richard D. Worth */ #if HAVE_CONFIG_H #include "config.h" #endif #include #include #ifdef HAVE_UNISTD_H #include #endif #include #include #include #include "cairo-test.h" #include "pdiff.h" #include "buffer-diff.h" /* Don't allow any differences greater than this value, even if pdiff * claims that the images are identical */ #define PERCEPTUAL_DIFF_THRESHOLD 25 /* Compare two buffers, returning the number of pixels that are * different and the maximum difference of any single color channel in * result_ret. * * This function should be rewritten to compare all formats supported by * cairo_format_t instead of taking a mask as a parameter. */ static void buffer_diff_core (const unsigned char *_buf_a, int stride_a, const unsigned char *_buf_b, int stride_b, unsigned char *_buf_diff, int stride_diff, int width, int height, uint32_t mask, buffer_diff_result_t *result_ret) { const uint32_t *buf_a = (const uint32_t*) _buf_a; const uint32_t *buf_b = (const uint32_t*) _buf_b; uint32_t *buf_diff = (uint32_t*) _buf_diff; int x, y; buffer_diff_result_t result = {0, 0}; stride_a /= sizeof (uint32_t); stride_b /= sizeof (uint32_t); stride_diff /= sizeof (uint32_t); for (y = 0; y < height; y++) { const uint32_t *row_a = buf_a + y * stride_a; const uint32_t *row_b = buf_b + y * stride_b; uint32_t *row = buf_diff + y * stride_diff; for (x = 0; x < width; x++) { /* check if the pixels are the same */ if ((row_a[x] & mask) != (row_b[x] & mask)) { int channel; uint32_t diff_pixel = 0; /* calculate a difference value for all 4 channels */ for (channel = 0; channel < 4; channel++) { int value_a = (row_a[x] >> (channel*8)) & 0xff; int value_b = (row_b[x] >> (channel*8)) & 0xff; unsigned int diff; diff = abs (value_a - value_b); if (diff > result.max_diff) result.max_diff = diff; diff *= 4; /* emphasize */ if (diff) diff += 128; /* make sure it's visible */ if (diff > 255) diff = 255; diff_pixel |= diff << (channel*8); } result.pixels_changed++; if ((diff_pixel & 0x00ffffff) == 0) { /* alpha only difference, convert to luminance */ uint8_t alpha = diff_pixel >> 24; diff_pixel = alpha * 0x010101; } row[x] = diff_pixel; } else { row[x] = 0; } row[x] |= 0xff000000; /* Set ALPHA to 100% (opaque) */ } } *result_ret = result; } /* Compares two image surfaces * * Provides number of pixels changed and maximum single-channel * difference in result. * * Also fills in a "diff" surface intended to visually show where the * images differ. */ static void compare_surfaces (const cairo_test_context_t *ctx, cairo_surface_t *surface_a, cairo_surface_t *surface_b, cairo_surface_t *surface_diff, buffer_diff_result_t *result) { /* These default values were taken straight from the * perceptualdiff program. We'll probably want to tune these as * necessary. */ double gamma = 2.2; double luminance = 100.0; double field_of_view = 45.0; int discernible_pixels_changed; /* First, we run cairo's old buffer_diff algorithm which looks for * pixel-perfect images, (we do this first since the test suite * runs about 3x slower if we run pdiff_compare first). */ buffer_diff_core (cairo_image_surface_get_data (surface_a), cairo_image_surface_get_stride (surface_a), cairo_image_surface_get_data (surface_b), cairo_image_surface_get_stride (surface_b), cairo_image_surface_get_data (surface_diff), cairo_image_surface_get_stride (surface_diff), cairo_image_surface_get_width (surface_a), cairo_image_surface_get_height (surface_a), cairo_surface_get_content (surface_a) & CAIRO_CONTENT_ALPHA ? 0xffffffff : 0x00ffffff, result); if (result->pixels_changed == 0) return; cairo_test_log (ctx, "%d pixels differ (with maximum difference of %d) from reference image\n", result->pixels_changed, result->max_diff); /* Then, if there are any different pixels, we give the pdiff code * a crack at the images. If it decides that there are no visually * discernible differences in any pixels, then we accept this * result as good enough. * * Only let pdiff have a crack at the comparison if the max difference * is lower than a threshold, otherwise some problems could be masked. */ if (result->max_diff < PERCEPTUAL_DIFF_THRESHOLD) { discernible_pixels_changed = pdiff_compare (surface_a, surface_b, gamma, luminance, field_of_view); if (discernible_pixels_changed == 0) { result->pixels_changed = 0; cairo_test_log (ctx, "But perceptual diff finds no visually discernible difference.\n" "Accepting result.\n"); } } } void buffer_diff_noalpha (const unsigned char *buf_a, const unsigned char *buf_b, unsigned char *buf_diff, int width, int height, int stride, buffer_diff_result_t *result) { buffer_diff_core(buf_a, stride, buf_b, stride, buf_diff, stride, width, height, 0x00ffffff, result); } static cairo_bool_t same_size (cairo_surface_t *a, cairo_surface_t *b) { unsigned int width_a, height_a; unsigned int width_b, height_b; width_a = cairo_image_surface_get_width (a); height_a = cairo_image_surface_get_height (a); width_b = cairo_image_surface_get_width (b); height_b = cairo_image_surface_get_height (b); return width_a == width_b && height_a == height_b; } /* Image comparison code courtesy of Richard Worth * Returns number of pixels changed, (or -1 on error). * Also saves a "diff" image intended to visually show where the * images differ. * * The return value simply indicates whether a check was successfully * made, (as opposed to a file-not-found condition or similar). It * does not indicate anything about how much the images differ. For * that, see result. * * One failure mode is if the two images provided do not have the same * dimensions. In this case, this function will return * CAIRO_STATUS_SURFACE_TYPE_MISMATCH (which is a bit of an abuse, but * oh well). */ cairo_status_t image_diff (const cairo_test_context_t *ctx, cairo_surface_t *surface_a, cairo_surface_t *surface_b, cairo_surface_t *surface_diff, buffer_diff_result_t *result) { if (cairo_surface_status (surface_a)) return cairo_surface_status (surface_a); if (cairo_surface_status (surface_b)) return cairo_surface_status (surface_b); if (cairo_surface_status (surface_diff)) return cairo_surface_status (surface_diff); if (! same_size (surface_a, surface_b) || ! same_size (surface_a, surface_diff)) { cairo_test_log (ctx, "Error: Image size mismatch\n"); return CAIRO_STATUS_SURFACE_TYPE_MISMATCH; } compare_surfaces (ctx, surface_a, surface_b, surface_diff, result); return CAIRO_STATUS_SUCCESS; }