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Bugfix #18733 & #18609 (revisited)

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New imbuf scaling code, advertised as "quick and quality" gave
inacceptable noise and rounding errors. 

Check this bugreport for images that show it well:
http://projects.blender.org/tracker/?func=detail&atid=125&aid=18609&group_id=9

For release, better disable this code and fall back on perfectly
working old code. :)
This commit is contained in:
Ton Roosendaal 2009-05-18 10:34:26 +00:00
parent cb96dc40e8
commit b1a393e815
1 changed files with 20 additions and 16 deletions
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36
source/blender/imbuf/intern/scaling.c
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@ -596,12 +596,12 @@ static void shrink_picture_byte(
y_counter = 65536;
for (y_src = 0; y_src < src_height; y_src++) {
unsigned char* line = src + y_src * 4 * src_width;
uintptr_t weight1y = 65536 - (y_dst & 0xffff);
uintptr_t weight2y = 65536 - weight1y;
uintptr_t weight1y = 65535 - (y_dst & 0xffff);
uintptr_t weight2y = 65535 - weight1y;
x_dst = 0;
for (x_src = 0; x_src < src_width; x_src++) {
uintptr_t weight1x = 65536 - (x_dst & 0xffff);
uintptr_t weight2x = 65536 - weight1x;
uintptr_t weight1x = 65535 - (x_dst & 0xffff);
uintptr_t weight2x = 65535 - weight1x;
uintptr_t x = x_dst >> 16;
@ -609,7 +609,7 @@ static void shrink_picture_byte(
w = (weight1y * weight1x) >> 16;
/* ensure correct rounding, without this you get ugly banding (ton) */
/* ensure correct rounding, without this you get ugly banding, or too low color values (ton) */
dst_line1[x].r += (line[0] * w + 32767) >> 16;
dst_line1[x].g += (line[1] * w + 32767) >> 16;
dst_line1[x].b += (line[2] * w + 32767) >> 16;
@ -647,18 +647,18 @@ static void shrink_picture_byte(
y_dst += dy_dst;
y_counter -= dy_dst;
if (y_counter < 0) {
int val;
uintptr_t x;
struct scale_outpix_byte * temp;
y_counter += 65536;
for (x=0; x < dst_width; x++) {
uintptr_t f = 0x80000000UL
/ dst_line1[x].weight;
*dst++ = (dst_line1[x].r * f) >> 15;
*dst++ = (dst_line1[x].g * f) >> 15;
*dst++ = (dst_line1[x].b * f) >> 15;
*dst++ = (dst_line1[x].a * f) >> 15;
uintptr_t f = 0x80000000UL / dst_line1[x].weight;
*dst++ = (val= (dst_line1[x].r * f) >> 15) > 255 ? 255: val;
*dst++ = (val= (dst_line1[x].g * f) >> 15) > 255 ? 255: val;
*dst++ = (val= (dst_line1[x].b * f) >> 15) > 255 ? 255: val;
*dst++ = (val= (dst_line1[x].a * f) >> 15) > 255 ? 255: val;
}
memset(dst_line1, 0, dst_width *
sizeof(struct scale_outpix_byte));
@ -668,13 +668,14 @@ static void shrink_picture_byte(
}
}
if (dst - dst_begin < dst_width * dst_height * 4) {
int val;
uintptr_t x;
for (x = 0; x < dst_width; x++) {
uintptr_t f = 0x80000000UL / dst_line1[x].weight;
*dst++ = (dst_line1[x].r * f) >> 15;
*dst++ = (dst_line1[x].g * f) >> 15;
*dst++ = (dst_line1[x].b * f) >> 15;
*dst++ = (dst_line1[x].a * f) >> 15;
*dst++ = (val= (dst_line1[x].r * f) >> 15) > 255 ? 255: val;
*dst++ = (val= (dst_line1[x].g * f) >> 15) > 255 ? 255: val;
*dst++ = (val= (dst_line1[x].b * f) >> 15) > 255 ? 255: val;
*dst++ = (val= (dst_line1[x].a * f) >> 15) > 255 ? 255: val;
}
}
MEM_freeN(dst_line1);
@ -912,6 +913,8 @@ static void q_scale_float(float* in, float* out, int in_width,
Should be comparable in speed to the ImBuf ..._fast functions at least
for byte-buffers.
NOTE: disabled, due to inacceptable inaccuracy and quality loss, see bug #18609 (ton)
*/
static int q_scale_linear_interpolation(
struct ImBuf *ibuf, int newx, int newy)
@ -1584,7 +1587,8 @@ struct ImBuf *IMB_scaleImBuf(struct ImBuf * ibuf, short newx, short newy)
scalefast_Z_ImBuf(ibuf, newx, newy);
/* try to scale common cases in a fast way */
if (q_scale_linear_interpolation(ibuf, newx, newy)) {
/* disabled, quality loss is inacceptable, see report #18609 (ton) */
if (0 && q_scale_linear_interpolation(ibuf, newx, newy)) {
return ibuf;
}