From 206d2abfdd8115f84e3e448ed25b6ff9c7e371d3 Mon Sep 17 00:00:00 2001 From: kiirala Date: Sat, 28 Mar 2009 11:35:16 +0000 Subject: [PATCH] Fixed some bad math in pixblock-scaler. Seems to fix shifted blurs --- src/display/pixblock-scaler.cpp | 181 +++++++++++++++----------------- 1 file changed, 83 insertions(+), 98 deletions(-) diff --git a/src/display/pixblock-scaler.cpp b/src/display/pixblock-scaler.cpp index 511104c43..767334935 100644 --- a/src/display/pixblock-scaler.cpp +++ b/src/display/pixblock-scaler.cpp @@ -22,57 +22,32 @@ using std::floor; namespace NR { struct RGBA { - int r, g, b, a; + double r, g, b, a; }; /** Calculates cubically interpolated value of the four given pixel values. - * The pixel values should be from four vertically adjacent pixels. - * If we are calculating a pixel, whose y-coordinate in source image is - * i, these pixel values a, b, c and d should come from lines - * floor(i) - 1, floor(i), floor(i) + 1, floor(i) + 2, respectively. - * Parameter len should be set to i. - * Returns the interpolated value in fixed point format with 8 bit - * decimal part. (24.8 assuming 32-bit int) + * The pixel values should be from four adjacent pixels in source image or + * four adjacent interpolated values. len should be the x- or y-coordinate + * (depending on interpolation direction) of the center of the target pixel + * in source image coordinates. */ __attribute__ ((const)) -inline static int sampley(unsigned const char a, unsigned const char b, - unsigned const char c, unsigned const char d, - const double len) +inline static double sample(double const a, double const b, + double const c, double const d, + double const len) { - double lenf = len - floor(len); - int sum = 0; - sum += (int)((((-1.0 / 3.0) * lenf + 4.0 / 5.0) * lenf - 7.0 / 15.0) - * lenf * 256 * a); - sum += (int)((((lenf - 9.0 / 5.0) * lenf - 1.0 / 5.0) * lenf + 1.0) - * 256 * b); - sum += (int)(((((1 - lenf) - 9.0 / 5.0) * (1 - lenf) - 1.0 / 5.0) - * (1 - lenf) + 1.0) * 256 * c); - sum += (int)((((-1.0 / 3.0) * (1 - lenf) + 4.0 / 5.0) * (1 - lenf) - - 7.0 / 15.0) * (1 - lenf) * 256 * d); - return sum; -} + double lena = 1.5 + (len - round(len)); + double lenb = 0.5 + (len - round(len)); + double lenc = 0.5 - (len - round(len)); + double lend = 1.5 - (len - round(len)); + double const f = -0.5; // corresponds to cubic Hermite spline + double sum = 0; + sum += ((((f * lena) - 5.0 * f) * lena + 8.0 * f) * lena - 4 * f) * a; + sum += (((f + 2.0) * lenb - (f + 3.0)) * lenb * lenb + 1.0) * b; + sum += (((f + 2.0) * lenc - (f + 3.0)) * lenc * lenc + 1.0) * c; + sum += ((((f * lend) - 5.0 * f) * lend + 8.0 * f) * lend - 4 * f) * d; -/** Calculates cubically interpolated value of the four given pixel values. - * The pixel values should be interpolated values from sampley, from four - * horizontally adjacent vertical lines. The parameters a, b, c and d - * should be in fixed point format with 8-bit decimal part. - * If we are calculating a pixel, whose x-coordinate in source image is - * i, these vertical lines from where a, b, c and d are calculated, should be - * floor(i) - 1, floor(i), floor(i) + 1, floor(i) + 2, respectively. - * Parameter len should be set to i. - * Returns the interpolated value in 8-bit format, ready to be written - * to output buffer. - */ -inline static int samplex(const int a, const int b, const int c, const int d, const double len) { - double lenf = len - floor(len); - int sum = 0; - sum += (int)(a * (((-1.0 / 3.0) * lenf + 4.0 / 5.0) * lenf - 7.0 / 15.0) * lenf); - sum += (int)(b * (((lenf - 9.0 / 5.0) * lenf - 1.0 / 5.0) * lenf + 1.0)); - sum += (int)(c * ((((1 - lenf) - 9.0 / 5.0) * (1 - lenf) - 1.0 / 5.0) * (1 - lenf) + 1.0)); - sum += (int)(d * (((-1.0 / 3.0) * (1 - lenf) + 4.0 / 5.0) * (1 - lenf) - 7.0 / 15.0) * (1 - lenf)); - //if (sum < 0) sum = 0; - //if (sum > 255 * 256) sum = 255 * 256; - return sum / 256; + return sum; } /** @@ -123,9 +98,10 @@ static void scale_bicubic_rgba(NRPixBlock *to, NRPixBlock *from) // which we should read int from_line[4]; for (int i = 0 ; i < 4 ; i++) { - if ((int)floor(from_y) + i - 1 >= 0) { - if ((int)floor(from_y) + i - 1 < from_height) { - from_line[i] = ((int)floor(from_y) + i - 1) * from->rs; + int fy_line = (int)round(from_y) + i - 2; + if (fy_line >= 0) { + if (fy_line < from_height) { + from_line[i] = fy_line * from->rs; } else { from_line[i] = (from_height - 1) * from->rs; } @@ -140,7 +116,7 @@ static void scale_bicubic_rgba(NRPixBlock *to, NRPixBlock *from) double from_x = to_x * from_stepx + from_stepx / 2; RGBA line[4]; for (int i = 0 ; i < 4 ; i++) { - int k = (int)floor(from_x) + i - 1; + int k = (int)round(from_x) + i - 2; if (k < 0) k = 0; if (k >= from_width) k = from_width - 1; k *= 4; @@ -148,36 +124,36 @@ static void scale_bicubic_rgba(NRPixBlock *to, NRPixBlock *from) _check_index(from, from_line[1] + k, __LINE__); _check_index(from, from_line[2] + k, __LINE__); _check_index(from, from_line[3] + k, __LINE__); - line[i].r = sampley(NR_PIXBLOCK_PX(from)[from_line[0] + k], - NR_PIXBLOCK_PX(from)[from_line[1] + k], - NR_PIXBLOCK_PX(from)[from_line[2] + k], - NR_PIXBLOCK_PX(from)[from_line[3] + k], - from_y); - line[i].g = sampley(NR_PIXBLOCK_PX(from)[from_line[0] + k + 1], - NR_PIXBLOCK_PX(from)[from_line[1] + k + 1], - NR_PIXBLOCK_PX(from)[from_line[2] + k + 1], - NR_PIXBLOCK_PX(from)[from_line[3] + k + 1], - from_y); - line[i].b = sampley(NR_PIXBLOCK_PX(from)[from_line[0] + k + 2], - NR_PIXBLOCK_PX(from)[from_line[1] + k + 2], - NR_PIXBLOCK_PX(from)[from_line[2] + k + 2], - NR_PIXBLOCK_PX(from)[from_line[3] + k + 2], - from_y); - line[i].a = sampley(NR_PIXBLOCK_PX(from)[from_line[0] + k + 3], - NR_PIXBLOCK_PX(from)[from_line[1] + k + 3], - NR_PIXBLOCK_PX(from)[from_line[2] + k + 3], - NR_PIXBLOCK_PX(from)[from_line[3] + k + 3], - from_y); + line[i].r = sample(NR_PIXBLOCK_PX(from)[from_line[0] + k], + NR_PIXBLOCK_PX(from)[from_line[1] + k], + NR_PIXBLOCK_PX(from)[from_line[2] + k], + NR_PIXBLOCK_PX(from)[from_line[3] + k], + from_y); + line[i].g = sample(NR_PIXBLOCK_PX(from)[from_line[0] + k + 1], + NR_PIXBLOCK_PX(from)[from_line[1] + k + 1], + NR_PIXBLOCK_PX(from)[from_line[2] + k + 1], + NR_PIXBLOCK_PX(from)[from_line[3] + k + 1], + from_y); + line[i].b = sample(NR_PIXBLOCK_PX(from)[from_line[0] + k + 2], + NR_PIXBLOCK_PX(from)[from_line[1] + k + 2], + NR_PIXBLOCK_PX(from)[from_line[2] + k + 2], + NR_PIXBLOCK_PX(from)[from_line[3] + k + 2], + from_y); + line[i].a = sample(NR_PIXBLOCK_PX(from)[from_line[0] + k + 3], + NR_PIXBLOCK_PX(from)[from_line[1] + k + 3], + NR_PIXBLOCK_PX(from)[from_line[2] + k + 3], + NR_PIXBLOCK_PX(from)[from_line[3] + k + 3], + from_y); } RGBA result; - result.r = samplex(line[0].r, line[1].r, line[2].r, line[3].r, - from_x); - result.g = samplex(line[0].g, line[1].g, line[2].g, line[3].g, - from_x); - result.b = samplex(line[0].b, line[1].b, line[2].b, line[3].b, - from_x); - result.a = samplex(line[0].a, line[1].a, line[2].a, line[3].a, - from_x); + result.r = round(sample(line[0].r, line[1].r, line[2].r, line[3].r, + from_x)); + result.g = round(sample(line[0].g, line[1].g, line[2].g, line[3].g, + from_x)); + result.b = round(sample(line[0].b, line[1].b, line[2].b, line[3].b, + from_x)); + result.a = round(sample(line[0].a, line[1].a, line[2].a, line[3].a, + from_x)); _check_index(to, to_y * to->rs + to_x * 4, __LINE__); @@ -188,17 +164,24 @@ static void scale_bicubic_rgba(NRPixBlock *to, NRPixBlock *from) * make sure, we don't exceed 100% per colour channel with * images that have premultiplied alpha */ - result.a = clamp(result.a); + int const alpha = clamp((int)result.a); - NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4] = clamp_alpha(result.r, result.a); - NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 1] = clamp_alpha(result.g, result.a); - NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 2] = clamp_alpha(result.b, result.a); - NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 3] = result.a; + NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4] + = clamp_alpha((int)result.r, alpha); + NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 1] + = clamp_alpha((int)result.g, alpha); + NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 2] + = clamp_alpha((int)result.b, alpha); + NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 3] = alpha; } else { - NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4] = clamp(result.r); - NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 1] = clamp(result.g); - NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 2] = clamp(result.b); - NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 3] = clamp(result.a); + NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4] + = clamp((int)result.r); + NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 1] + = clamp((int)result.g); + NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 2] + = clamp((int)result.b); + NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 3] + = clamp((int)result.a); } } } @@ -234,9 +217,10 @@ void scale_bicubic_alpha(NRPixBlock *to, NRPixBlock *from) // which we should read int from_line[4]; for (int i = 0 ; i < 4 ; i++) { - if ((int)floor(from_y) + i - 1 >= 0) { - if ((int)floor(from_y) + i - 1 < from_height) { - from_line[i] = ((int)floor(from_y) + i - 1) * from->rs; + int fy_line = (int)round(from_y) + i - 2; + if (fy_line >= 0) { + if (fy_line < from_height) { + from_line[i] = fy_line * from->rs; } else { from_line[i] = (from_height - 1) * from->rs; } @@ -249,28 +233,29 @@ void scale_bicubic_alpha(NRPixBlock *to, NRPixBlock *from) // bicubic interpolation and set the pixel value in destination image for (int to_x = 0 ; to_x < to_width ; to_x++) { double from_x = to_x * from_stepx + from_stepx / 2; - int line[4]; + double line[4]; for (int i = 0 ; i < 4 ; i++) { - int k = (int)floor(from_x) + i - 1; + int k = (int)round(from_x) + i - 2; if (k < 0) k = 0; if (k >= from_width) k = from_width - 1; _check_index(from, from_line[0] + k, __LINE__); _check_index(from, from_line[1] + k, __LINE__); _check_index(from, from_line[2] + k, __LINE__); _check_index(from, from_line[3] + k, __LINE__); - line[i] = sampley(NR_PIXBLOCK_PX(from)[from_line[0] + k], - NR_PIXBLOCK_PX(from)[from_line[1] + k], - NR_PIXBLOCK_PX(from)[from_line[2] + k], - NR_PIXBLOCK_PX(from)[from_line[3] + k], - from_y); + line[i] = sample(NR_PIXBLOCK_PX(from)[from_line[0] + k], + NR_PIXBLOCK_PX(from)[from_line[1] + k], + NR_PIXBLOCK_PX(from)[from_line[2] + k], + NR_PIXBLOCK_PX(from)[from_line[3] + k], + from_y); } int result; - result = samplex(line[0], line[1], line[2], line[3], - from_x); + result = (int)round(sample(line[0], line[1], line[2], line[3], + from_x)); _check_index(to, to_y * to->rs + to_x, __LINE__); - NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x] = Inkscape::Filters::clamp(result); + NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x] + = Inkscape::Filters::clamp(result); } } } -- 2.30.2