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libpng16/libpng-rgb_to_gray-checks.patch

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http://sourceforge.net/p/libpng/code/ci/a21a5b22c10b900d44d40fe30a203302b2a67f8b/
--- contrib/libtests/pngvalid.c
+++ contrib/libtests/pngvalid.c
@@ -258,7 +258,7 @@
make_random_bytes(seed, bytes, 4);
}
-#ifdef PNG_READ_SUPPORTED
+#if defined PNG_READ_SUPPORTED || defined PNG_WRITE_tRNS_SUPPORTED
static void
randomize(void *pv, size_t size)
{
@@ -267,7 +267,9 @@
}
#define RANDOMIZE(this) randomize(&(this), sizeof (this))
-
+#endif /* READ || WRITE_tRNS */
+
+#ifdef PNG_READ_SUPPORTED
static unsigned int
random_mod(unsigned int max)
{
@@ -295,7 +297,8 @@
/* A numeric ID based on PNG file characteristics. The 'do_interlace' field
* simply records whether pngvalid did the interlace itself or whether it
* was done by libpng. Width and height must be less than 256. 'palette' is an
- * index of the palette to use for formats with a palette (0 otherwise.)
+ * index of the palette to use for formats with a palette otherwise a boolean
+ * indicating if a tRNS chunk was generated.
*/
#define FILEID(col, depth, palette, interlace, width, height, do_interlace) \
((png_uint_32)((col) + ((depth)<<3) + ((palette)<<8) + ((interlace)<<13) + \
@@ -316,12 +319,16 @@
png_uint_32 w, png_uint_32 h, int do_interlace)
{
pos = safecat(buffer, bufsize, pos, colour_types[colour_type]);
- if (npalette > 0)
+ if (colour_type == 3) /* must have a palette */
{
pos = safecat(buffer, bufsize, pos, "[");
pos = safecatn(buffer, bufsize, pos, npalette);
pos = safecat(buffer, bufsize, pos, "]");
}
+
+ else if (npalette != 0)
+ pos = safecat(buffer, bufsize, pos, "+tRNS");
+
pos = safecat(buffer, bufsize, pos, " ");
pos = safecatn(buffer, bufsize, pos, bit_depth);
pos = safecat(buffer, bufsize, pos, " bit");
@@ -378,25 +385,32 @@
static int
next_format(png_bytep colour_type, png_bytep bit_depth,
- unsigned int* palette_number, int no_low_depth_gray)
+ unsigned int* palette_number, int low_depth_gray, int tRNS)
{
if (*bit_depth == 0)
{
*colour_type = 0;
- if (no_low_depth_gray)
+ if (low_depth_gray)
+ *bit_depth = 1;
+ else
*bit_depth = 8;
- else
- *bit_depth = 1;
*palette_number = 0;
return 1;
}
- if (*colour_type == 3)
- {
- /* Add multiple palettes for colour type 3. */
- if (++*palette_number < PALETTE_COUNT(*bit_depth))
+ if (*colour_type < 4/*no alpha channel*/)
+ {
+ /* Add multiple palettes for colour type 3, one image with tRNS
+ * and one without for other non-alpha formats:
+ */
+ unsigned int pn = ++*palette_number;
+ png_byte ct = *colour_type;
+
+ if (((ct == 0/*GRAY*/ || ct/*RGB*/ == 2) && tRNS && pn < 2) ||
+ (ct == 3/*PALETTE*/ && pn < PALETTE_COUNT(*bit_depth)))
return 1;
+ /* No: next bit depth */
*palette_number = 0;
}
@@ -1959,6 +1973,7 @@
/* Run tests on reading with a combination of transforms, */
unsigned int test_transform :1;
+ unsigned int test_tRNS :1; /* Includes tRNS images */
/* When to use the use_input_precision option, this controls the gamma
* validation code checks. If set any value that is within the transformed
@@ -1989,6 +2004,16 @@
unsigned int test_gamma_alpha_mode :1;
unsigned int test_gamma_expand16 :1;
unsigned int test_exhaustive :1;
+
+ /* Whether or not to run the low-bit-depth grayscale tests. This fail on
+ * gamma images in some cases because of gross inaccuracies in the grayscale
+ * gamma handling for low bit depth.
+ */
+ unsigned int test_lbg :1;
+ unsigned int test_lbg_gamma_threshold :1;
+ unsigned int test_lbg_gamma_transform :1;
+ unsigned int test_lbg_gamma_sbit :1;
+ unsigned int test_lbg_gamma_composition :1;
unsigned int log :1; /* Log max error */
@@ -2042,6 +2067,11 @@
pm->test_standard = 0;
pm->test_size = 0;
pm->test_transform = 0;
+# ifdef PNG_WRITE_tRNS_SUPPORTED
+ pm->test_tRNS = 1;
+# else
+ pm->test_tRNS = 0;
+# endif
pm->use_input_precision = 0;
pm->use_input_precision_sbit = 0;
pm->use_input_precision_16to8 = 0;
@@ -2054,6 +2084,11 @@
pm->test_gamma_background = 0;
pm->test_gamma_alpha_mode = 0;
pm->test_gamma_expand16 = 0;
+ pm->test_lbg = 1;
+ pm->test_lbg_gamma_threshold = 1;
+ pm->test_lbg_gamma_transform = 1;
+ pm->test_lbg_gamma_sbit = 1;
+ pm->test_lbg_gamma_composition = 1;
pm->test_exhaustive = 0;
pm->log = 0;
@@ -3192,6 +3227,45 @@
}
}
+#ifdef PNG_WRITE_tRNS_SUPPORTED
+static void
+set_random_tRNS(png_structp pp, png_infop pi, PNG_CONST png_byte colour_type,
+ PNG_CONST int bit_depth)
+{
+ /* To make this useful the tRNS color needs to match at least one pixel.
+ * Random values are fine for gray, including the 16-bit case where we know
+ * that the test image contains all the gray values. For RGB we need more
+ * method as only 65536 different RGB values are generated.
+ */
+ png_color_16 tRNS;
+ const png_uint_16 mask = (png_uint_16)((1U << bit_depth)-1);
+
+ RANDOMIZE(tRNS);
+
+ if (colour_type & 2/*RGB*/)
+ {
+ if (bit_depth == 8)
+ {
+ tRNS.blue = tRNS.red ^ tRNS.green;
+ tRNS.red &= mask;
+ tRNS.green &= mask;
+ tRNS.blue &= mask;
+ }
+
+ else /* bit_depth == 16 */
+ {
+ tRNS.green = (png_uint_16)(tRNS.red * 257);
+ tRNS.blue = (png_uint_16)(tRNS.green * 17);
+ }
+ }
+
+ else
+ tRNS.gray &= mask;
+
+ png_set_tRNS(pp, pi, NULL, 0, &tRNS);
+}
+#endif
+
/* The number of passes is related to the interlace type. There was no libpng
* API to determine this prior to 1.5, so we need an inquiry function:
*/
@@ -3525,6 +3599,11 @@
if (colour_type == 3) /* palette */
init_standard_palette(ps, pp, pi, 1U << bit_depth, 1/*do tRNS*/);
+# ifdef PNG_WRITE_tRNS_SUPPORTED
+ else if (palette_number)
+ set_random_tRNS(pp, pi, colour_type, bit_depth);
+# endif
+
png_write_info(pp, pi);
if (png_get_rowbytes(pp, pi) !=
@@ -3598,19 +3677,20 @@
}
static void
-make_transform_images(png_store *ps)
+make_transform_images(png_modifier *pm)
{
png_byte colour_type = 0;
png_byte bit_depth = 0;
unsigned int palette_number = 0;
/* This is in case of errors. */
- safecat(ps->test, sizeof ps->test, 0, "make standard images");
+ safecat(pm->this.test, sizeof pm->this.test, 0, "make standard images");
/* Use next_format to enumerate all the combinations we test, including
- * generating multiple low bit depth palette images.
- */
- while (next_format(&colour_type, &bit_depth, &palette_number, 0))
+ * generating multiple low bit depth palette images. Non-A images (palette
+ * and direct) are created with and without tRNS chunks.
+ */
+ while (next_format(&colour_type, &bit_depth, &palette_number, 1, 1))
{
int interlace_type;
@@ -3621,7 +3701,7 @@
standard_name(name, sizeof name, 0, colour_type, bit_depth,
palette_number, interlace_type, 0, 0, 0);
- make_transform_image(ps, colour_type, bit_depth, palette_number,
+ make_transform_image(&pm->this, colour_type, bit_depth, palette_number,
interlace_type, name);
}
}
@@ -4287,6 +4367,7 @@
size_t cbRow; /* Bytes in a row of the output image */
int do_interlace; /* Do interlacing internally */
int is_transparent; /* Transparency information was present. */
+ int has_tRNS; /* color type GRAY or RGB with a tRNS chunk. */
int speed; /* Doing a speed test */
int use_update_info;/* Call update_info, not start_image */
struct
@@ -4619,14 +4700,14 @@
case 0:
dp->transparent.red = dp->transparent.green = dp->transparent.blue =
trans_color->gray;
- dp->is_transparent = 1;
+ dp->has_tRNS = 1;
break;
case 2:
dp->transparent.red = trans_color->red;
dp->transparent.green = trans_color->green;
dp->transparent.blue = trans_color->blue;
- dp->is_transparent = 1;
+ dp->has_tRNS = 1;
break;
case 3:
@@ -5518,7 +5599,7 @@
if (this->colour_type == PNG_COLOR_TYPE_GRAY)
{
if (this->bit_depth < 8)
- this->bit_depth = 8;
+ this->bit_depth = this->sample_depth = 8;
if (this->have_tRNS)
{
@@ -5553,9 +5634,11 @@
this->alphaf = 0;
else
this->alphaf = 1;
-
- this->colour_type = PNG_COLOR_TYPE_RGB_ALPHA;
}
+ else
+ this->alphaf = 1;
+
+ this->colour_type = PNG_COLOR_TYPE_RGB_ALPHA;
}
/* The error in the alpha is zero and the sBIT value comes from the
@@ -5848,8 +5931,9 @@
/* If png_set_filler is in action then fake the output color type to include
* an alpha channel where appropriate.
*/
- if (dp->output_bit_depth >= 8 && (dp->output_colour_type == PNG_COLOR_TYPE_RGB ||
- dp->output_colour_type == PNG_COLOR_TYPE_GRAY) && dp->this.filler)
+ if (dp->output_bit_depth >= 8 &&
+ (dp->output_colour_type == PNG_COLOR_TYPE_RGB ||
+ dp->output_colour_type == PNG_COLOR_TYPE_GRAY) && dp->this.filler)
dp->output_colour_type |= 4;
/* Validate the combination of colour type and bit depth that we are getting
@@ -6372,6 +6456,13 @@
transform_display *that, png_structp pp, png_infop pi)
{
png_set_tRNS_to_alpha(pp);
+
+ /* If there was a tRNS chunk that would get expanded and add an alpha
+ * channel is_transparent must be updated:
+ */
+ if (that->this.has_tRNS)
+ that->this.is_transparent = 1;
+
this->next->set(this->next, that, pp, pi);
}
@@ -6430,6 +6521,7 @@
transform_display *that, png_structp pp, png_infop pi)
{
png_set_gray_to_rgb(pp);
+ /* NOTE: this doesn't result in tRNS expansion. */
this->next->set(this->next, that, pp, pi);
}
@@ -6489,6 +6581,10 @@
transform_display *that, png_structp pp, png_infop pi)
{
png_set_expand(pp);
+
+ if (that->this.has_tRNS)
+ that->this.is_transparent = 1;
+
this->next->set(this->next, that, pp, pi);
}
@@ -6539,6 +6635,7 @@
png_infop pi)
{
png_set_expand_gray_1_2_4_to_8(pp);
+ /* NOTE: don't expect this to expand tRNS */
this->next->set(this->next, that, pp, pi);
}
@@ -6570,6 +6667,11 @@
transform_display *that, png_structp pp, png_infop pi)
{
png_set_expand_16(pp);
+
+ /* NOTE: at present libpng does SET_EXPAND as well, so tRNS is expanded. */
+ if (that->this.has_tRNS)
+ that->this.is_transparent = 1;
+
this->next->set(this->next, that, pp, pi);
}
@@ -6940,14 +7042,14 @@
* When DIGITIZE is set because a pre-1.7 version of libpng is being
* tested allow a bigger slack.
*
- * NOTE: this magic number was determined by experiment to be 1.25.
- * There's no great merit to the value below, however it only affects
- * the limit used for checking for internal calculation errors, not
- * the actual limit imposed by pngvalid on the output errors.
+ * NOTE: this magic number was determined by experiment to be about
+ * 1.263. There's no great merit to the value below, however it only
+ * affects the limit used for checking for internal calculation errors,
+ * not the actual limit imposed by pngvalid on the output errors.
*/
that->pm->limit += pow(
# if DIGITIZE
- 1.25
+ 1.3
# else
1.0
# endif
@@ -7111,7 +7213,8 @@
const unsigned int sample_depth = that->sample_depth;
const unsigned int calc_depth = (pm->assume_16_bit_calculations ? 16 :
sample_depth);
- const unsigned int gamma_depth = (sample_depth == 16 ? 16 :
+ const unsigned int gamma_depth = (sample_depth == 16 ?
+ PNG_MAX_GAMMA_8 :
(pm->assume_16_bit_calculations ? PNG_MAX_GAMMA_8 : sample_depth));
int isgray;
double r, g, b;
@@ -7125,56 +7228,73 @@
* will be identical after this operation if there is only one
* transform, feel free to delete the png_error checks on this below in
* the future (this is just me trying to ensure it works!)
+ *
+ * Interval arithmetic is exact, but to implement it it must be
+ * possible to control the floating point implementation rounding mode.
+ * This cannot be done in ANSI-C, so instead I reduce the 'lo' values
+ * by DBL_EPSILON and increase the 'hi' values by the same.
*/
+# define DD(v,d,r) (digitize(v*(1-DBL_EPSILON), d, r) * (1-DBL_EPSILON))
+# define DU(v,d,r) (digitize(v*(1+DBL_EPSILON), d, r) * (1+DBL_EPSILON))
+
r = rlo = rhi = that->redf;
rlo -= that->rede;
- rlo = digitize(rlo, calc_depth, 1/*round*/);
+ rlo = DD(rlo, calc_depth, 1/*round*/);
rhi += that->rede;
- rhi = digitize(rhi, calc_depth, 1/*round*/);
+ rhi = DU(rhi, calc_depth, 1/*round*/);
g = glo = ghi = that->greenf;
glo -= that->greene;
- glo = digitize(glo, calc_depth, 1/*round*/);
+ glo = DD(glo, calc_depth, 1/*round*/);
ghi += that->greene;
- ghi = digitize(ghi, calc_depth, 1/*round*/);
+ ghi = DU(ghi, calc_depth, 1/*round*/);
b = blo = bhi = that->bluef;
blo -= that->bluee;
- blo = digitize(blo, calc_depth, 1/*round*/);
+ blo = DD(blo, calc_depth, 1/*round*/);
bhi += that->greene;
- bhi = digitize(bhi, calc_depth, 1/*round*/);
+ bhi = DU(bhi, calc_depth, 1/*round*/);
isgray = r==g && g==b;
if (data.gamma != 1)
{
PNG_CONST double power = 1/data.gamma;
- PNG_CONST double abse = calc_depth == 16 ? .5/65535 : .5/255;
-
- /* 'abse' is the absolute error permitted in linear calculations. It
- * is used here to capture the error permitted in the handling
- * (undoing) of the gamma encoding. Once again digitization occurs
- * to handle the upper and lower bounds of the values. This is
- * where the real errors are introduced.
+ PNG_CONST double abse = .5/(sample_depth == 16 ? 65535 : 255);
+
+ /* If a gamma calculation is done it is done using lookup tables of
+ * precision gamma_depth, so the already digitized value above may
+ * need to be further digitized here.
*/
+ if (gamma_depth != calc_depth)
+ {
+ rlo = DD(rlo, gamma_depth, 0/*truncate*/);
+ rhi = DU(rhi, gamma_depth, 0/*truncate*/);
+ glo = DD(glo, gamma_depth, 0/*truncate*/);
+ ghi = DU(ghi, gamma_depth, 0/*truncate*/);
+ blo = DD(blo, gamma_depth, 0/*truncate*/);
+ bhi = DU(bhi, gamma_depth, 0/*truncate*/);
+ }
+
+ /* 'abse' is the error in the gamma table calculation itself. */
r = pow(r, power);
- rlo = digitize(pow(rlo, power)-abse, calc_depth, 1);
- rhi = digitize(pow(rhi, power)+abse, calc_depth, 1);
+ rlo = DD(pow(rlo, power)-abse, calc_depth, 1);
+ rhi = DU(pow(rhi, power)+abse, calc_depth, 1);
g = pow(g, power);
- glo = digitize(pow(glo, power)-abse, calc_depth, 1);
- ghi = digitize(pow(ghi, power)+abse, calc_depth, 1);
+ glo = DD(pow(glo, power)-abse, calc_depth, 1);
+ ghi = DU(pow(ghi, power)+abse, calc_depth, 1);
b = pow(b, power);
- blo = digitize(pow(blo, power)-abse, calc_depth, 1);
- bhi = digitize(pow(bhi, power)+abse, calc_depth, 1);
+ blo = DD(pow(blo, power)-abse, calc_depth, 1);
+ bhi = DU(pow(bhi, power)+abse, calc_depth, 1);
}
/* Now calculate the actual gray values. Although the error in the
* coefficients depends on whether they were specified on the command
* line (in which case truncation to 15 bits happened) or not (rounding
* was used) the maxium error in an individual coefficient is always
- * 1/32768, because even in the rounding case the requirement that
+ * 2/32768, because even in the rounding case the requirement that
* coefficients add up to 32768 can cause a larger rounding error.
*
* The only time when rounding doesn't occur in 1.5.5 and later is when
@@ -7185,19 +7305,19 @@
{
PNG_CONST int do_round = data.gamma != 1 || calc_depth == 16;
- PNG_CONST double ce = 1. / 32768;
-
- graylo = digitize(rlo * (data.red_coefficient-ce) +
+ PNG_CONST double ce = 2. / 32768;
+
+ graylo = DD(rlo * (data.red_coefficient-ce) +
glo * (data.green_coefficient-ce) +
- blo * (data.blue_coefficient-ce), gamma_depth, do_round);
- if (graylo <= 0)
- graylo = 0;
-
- grayhi = digitize(rhi * (data.red_coefficient+ce) +
+ blo * (data.blue_coefficient-ce), calc_depth, do_round);
+ if (graylo > gray) /* always accept the right answer */
+ graylo = gray;
+
+ grayhi = DU(rhi * (data.red_coefficient+ce) +
ghi * (data.green_coefficient+ce) +
- bhi * (data.blue_coefficient+ce), gamma_depth, do_round);
- if (grayhi >= 1)
- grayhi = 1;
+ bhi * (data.blue_coefficient+ce), calc_depth, do_round);
+ if (grayhi < gray)
+ grayhi = gray;
}
/* And invert the gamma. */
@@ -7205,10 +7325,24 @@
{
PNG_CONST double power = data.gamma;
+ /* And this happens yet again, shifting the values once more. */
+ if (gamma_depth != sample_depth)
+ {
+ rlo = DD(rlo, gamma_depth, 0/*truncate*/);
+ rhi = DU(rhi, gamma_depth, 0/*truncate*/);
+ glo = DD(glo, gamma_depth, 0/*truncate*/);
+ ghi = DU(ghi, gamma_depth, 0/*truncate*/);
+ blo = DD(blo, gamma_depth, 0/*truncate*/);
+ bhi = DU(bhi, gamma_depth, 0/*truncate*/);
+ }
+
gray = pow(gray, power);
- graylo = digitize(pow(graylo, power), sample_depth, 1);
- grayhi = digitize(pow(grayhi, power), sample_depth, 1);
+ graylo = DD(pow(graylo, power), sample_depth, 1);
+ grayhi = DU(pow(grayhi, power), sample_depth, 1);
}
+
+# undef DD
+# undef DU
/* Now the error can be calculated.
*
@@ -7260,16 +7394,28 @@
{
/* There is no need to do the conversions to and from linear space,
* so the calculation should be a lot more accurate. There is a
- * built in 1/32768 error in the coefficients because they only have
- * 15 bits and are adjusted to make sure they add up to 32768, so
- * the result may have an additional error up to 1/32768. (Note
- * that adding the 1/32768 here avoids needing to increase the
- * global error limits to take this into account.)
+ * built in error in the coefficients because they only have 15 bits
+ * and are adjusted to make sure they add up to 32768. This
+ * involves a integer calculation with truncation of the form:
+ *
+ * ((int)(coefficient * 100000) * 32768)/100000
+ *
+ * This is done to the red and green coefficients (the ones
+ * provided to the API) then blue is calculated from them so the
+ * result adds up to 32768. In the worst case this can result in
+ * a -1 error in red and green and a +2 error in blue. Consequently
+ * the worst case in the calculation below is 2/32768 error.
+ *
+ * TODO: consider fixing this in libpng by rounding the calculation
+ * limiting the error to 1/32768.
+ *
+ * Handling this by adding 2/32768 here avoids needing to increase
+ * the global error limits to take this into account.)
*/
gray = r * data.red_coefficient + g * data.green_coefficient +
b * data.blue_coefficient;
err = re * data.red_coefficient + ge * data.green_coefficient +
- be * data.blue_coefficient + 1./32768 + gray * 5 * DBL_EPSILON;
+ be * data.blue_coefficient + 2./32768 + gray * 5 * DBL_EPSILON;
}
else
@@ -7304,7 +7450,7 @@
* previously added input quantization error at this point.
*/
gray = r * data.red_coefficient + g * data.green_coefficient +
- b * data.blue_coefficient - 1./32768 - out_qe;
+ b * data.blue_coefficient - 2./32768 - out_qe;
if (gray <= 0)
gray = 0;
else
@@ -7314,7 +7460,7 @@
}
grayhi = rhi * data.red_coefficient + ghi * data.green_coefficient +
- bhi * data.blue_coefficient + 1./32768 + out_qe;
+ bhi * data.blue_coefficient + 2./32768 + out_qe;
grayhi *= (1 + 6 * DBL_EPSILON);
if (grayhi >= 1)
grayhi = 1;
@@ -7429,6 +7575,9 @@
else
{
+ if (that->this.has_tRNS)
+ that->this.is_transparent = 1;
+
bit_depth = that->this.bit_depth;
expand = 1;
}
@@ -7506,13 +7655,13 @@
/* Remove the alpha type and set the alpha (not in that order.) */
that->alphaf = 1;
that->alphae = 0;
-
- if (that->colour_type == PNG_COLOR_TYPE_RGB_ALPHA)
- that->colour_type = PNG_COLOR_TYPE_RGB;
- else if (that->colour_type == PNG_COLOR_TYPE_GRAY_ALPHA)
- that->colour_type = PNG_COLOR_TYPE_GRAY;
- /* PNG_COLOR_TYPE_PALETTE is not changed */
- }
+ }
+
+ if (that->colour_type == PNG_COLOR_TYPE_RGB_ALPHA)
+ that->colour_type = PNG_COLOR_TYPE_RGB;
+ else if (that->colour_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+ that->colour_type = PNG_COLOR_TYPE_GRAY;
+ /* PNG_COLOR_TYPE_PALETTE is not changed */
this->next->mod(this->next, that, pp, display);
}
@@ -8301,7 +8450,8 @@
png_byte bit_depth = 0;
unsigned int palette_number = 0;
- while (next_format(&colour_type, &bit_depth, &palette_number, 0))
+ while (next_format(&colour_type, &bit_depth, &palette_number, pm->test_lbg,
+ pm->test_tRNS))
{
png_uint_32 counter = 0;
size_t base_pos;
@@ -8604,7 +8754,9 @@
vi->outlog = outlog(dp->pm, in_depth, out_depth);
if ((dp->this.colour_type & PNG_COLOR_MASK_ALPHA) != 0 ||
- (dp->this.colour_type == 3 && dp->this.is_transparent))
+ (dp->this.colour_type == 3 && dp->this.is_transparent) ||
+ ((dp->this.colour_type == 0 || dp->this.colour_type == 2) &&
+ dp->this.has_tRNS))
{
vi->do_background = dp->do_background;
@@ -8634,7 +8786,7 @@
vi->background_blue = b;
}
}
- else
+ else /* Do not expect any background processing */
vi->do_background = 0;
if (vi->do_background == 0)
@@ -9350,6 +9502,7 @@
png_uint_32 y;
PNG_CONST store_palette_entry *in_palette = dp->this.palette;
PNG_CONST int in_is_transparent = dp->this.is_transparent;
+ int process_tRNS;
int out_npalette = -1;
int out_is_transparent = 0; /* Just refers to the palette case */
store_palette out_palette;
@@ -9365,6 +9518,7 @@
processing = (vi.gamma_correction > 0 && !dp->threshold_test)
|| in_bd != out_bd || in_ct != out_ct || vi.do_background;
+ process_tRNS = dp->this.has_tRNS && vi.do_background;
/* TODO: FIX THIS: MAJOR BUG! If the transformations all happen inside
* the palette there is no way of finding out, because libpng fails to
@@ -9403,8 +9557,8 @@
/* Handle input alpha - png_set_background will cause the output
* alpha to disappear so there is nothing to check.
*/
- if ((in_ct & PNG_COLOR_MASK_ALPHA) != 0 || (in_ct == 3 &&
- in_is_transparent))
+ if ((in_ct & PNG_COLOR_MASK_ALPHA) != 0 ||
+ (in_ct == 3 && in_is_transparent))
{
PNG_CONST unsigned int input_alpha = in_ct == 3 ?
dp->this.palette[in_index].alpha :
@@ -9433,6 +9587,35 @@
*/
alpha = input_alpha >> vi.isbit_shift;
alpha /= vi.sbit_max;
+ }
+ }
+
+ else if (process_tRNS)
+ {
+ /* alpha needs to be set appropriately for this pixel, it is
+ * currently 1 and needs to be 0 for an input pixel which matches
+ * the values in tRNS.
+ */
+ switch (in_ct)
+ {
+ case 0: /* gray */
+ if (sample(std, in_ct, in_bd, x, 0, 0, 0) ==
+ dp->this.transparent.red)
+ alpha = 0;
+ break;
+
+ case 2: /* RGB */
+ if (sample(std, in_ct, in_bd, x, 0, 0, 0) ==
+ dp->this.transparent.red &&
+ sample(std, in_ct, in_bd, x, 1, 0, 0) ==
+ dp->this.transparent.green &&
+ sample(std, in_ct, in_bd, x, 2, 0, 0) ==
+ dp->this.transparent.blue)
+ alpha = 0;
+ break;
+
+ default:
+ break;
}
}
@@ -9545,7 +9728,7 @@
modification_reset(d.pm->modifications);
- /* Get a png_struct for writing the image. */
+ /* Get a png_struct for reading the image. */
pp = set_modifier_for_read(d.pm, &pi, d.this.id, name);
standard_palette_init(&d.this);
@@ -9684,9 +9867,13 @@
/* Don't test more than one instance of each palette - it's pointless, in
* fact this test is somewhat excessive since libpng doesn't make this
* decision based on colour type or bit depth!
- */
- while (next_format(&colour_type, &bit_depth, &palette_number, 1/*gamma*/))
- if (palette_number == 0)
+ *
+ * CHANGED: now test two palettes and, as a side effect, images with and
+ * without tRNS.
+ */
+ while (next_format(&colour_type, &bit_depth, &palette_number,
+ pm->test_lbg_gamma_threshold, pm->test_tRNS))
+ if (palette_number < 2)
{
double test_gamma = 1.0;
while (test_gamma >= .4)
@@ -9746,7 +9933,8 @@
png_byte bit_depth = 0;
unsigned int palette_number = 0;
- while (next_format(&colour_type, &bit_depth, &palette_number, 1/*gamma*/))
+ while (next_format(&colour_type, &bit_depth, &palette_number,
+ pm->test_lbg_gamma_transform, pm->test_tRNS))
{
unsigned int i, j;
@@ -9776,7 +9964,8 @@
png_byte colour_type = 0, bit_depth = 0;
unsigned int npalette = 0;
- while (next_format(&colour_type, &bit_depth, &npalette, 1/*gamma*/))
+ while (next_format(&colour_type, &bit_depth, &npalette,
+ pm->test_lbg_gamma_sbit, pm->test_tRNS))
if ((colour_type & PNG_COLOR_MASK_ALPHA) == 0 &&
((colour_type == 3 && sbit < 8) ||
(colour_type != 3 && sbit < bit_depth)))
@@ -9967,8 +10156,17 @@
}
background.index = 193; /* rgb(193,193,193) to detect errors */
+
if (!(colour_type & PNG_COLOR_MASK_COLOR))
{
+ /* Because, currently, png_set_background is always called with
+ * 'need_expand' false in this case and because the gamma test itself
+ * doesn't cause an expand to 8-bit for lower bit depths the colour must
+ * be reduced to the correct range.
+ */
+ if (bit_depth < 8)
+ background.gray &= (png_uint_16)((1U << bit_depth)-1);
+
/* Grayscale input, we do not convert to RGB (TBD), so we must set the
* background to gray - else libpng seems to fail.
*/
@@ -10017,9 +10215,18 @@
/* Skip the non-alpha cases - there is no setting of a transparency colour at
* present.
- */
- while (next_format(&colour_type, &bit_depth, &palette_number, 1/*gamma*/))
- if ((colour_type & PNG_COLOR_MASK_ALPHA) != 0)
+ *
+ * TODO: incorrect; the palette case sets tRNS and, now RGB and gray do,
+ * however the palette case fails miserably so is commented out below.
+ */
+ while (next_format(&colour_type, &bit_depth, &palette_number,
+ pm->test_lbg_gamma_composition, pm->test_tRNS))
+ if ((colour_type & PNG_COLOR_MASK_ALPHA) != 0
+#if 0 /* TODO: FIXME */
+ /*TODO: FIXME: this should work */
+ || colour_type == 3
+#endif
+ || (colour_type != 3 && palette_number != 0))
{
unsigned int i, j;
@@ -10751,6 +10958,18 @@
pm.ngammas = ARRAY_SIZE(gammas);
pm.ngamma_tests = 0; /* default to off */
+ /* Low bit depth gray images don't do well in the gamma tests, until
+ * this is fixed turn them off for some gamma cases:
+ */
+# ifdef PNG_WRITE_tRNS_SUPPORTED
+ pm.test_tRNS = 1;
+# endif
+ pm.test_lbg = 0;
+ pm.test_lbg_gamma_threshold = 1;
+ pm.test_lbg_gamma_transform = 0/*PNG_LIBPNG_VER >= 10700*/;
+ pm.test_lbg_gamma_sbit = 1;
+ pm.test_lbg_gamma_composition = 0;
+
/* And the test encodings */
pm.encodings = test_encodings;
pm.nencodings = ARRAY_SIZE(test_encodings);
@@ -10863,7 +11082,7 @@
pm.test_gamma_transform = 1;
pm.test_gamma_sbit = 1;
pm.test_gamma_scale16 = 1;
- pm.test_gamma_background = 1;
+ pm.test_gamma_background = 1; /* composition */
pm.test_gamma_alpha_mode = 1;
}
@@ -10911,6 +11130,24 @@
else if (strcmp(*argv, "--noexpand16") == 0)
pm.test_gamma_expand16 = 0;
+
+ else if (strcmp(*argv, "--low-depth-gray") == 0)
+ pm.test_lbg = pm.test_lbg_gamma_threshold =
+ pm.test_lbg_gamma_transform = pm.test_lbg_gamma_sbit =
+ pm.test_lbg_gamma_composition = 1;
+
+ else if (strcmp(*argv, "--nolow-depth-gray") == 0)
+ pm.test_lbg = pm.test_lbg_gamma_threshold =
+ pm.test_lbg_gamma_transform = pm.test_lbg_gamma_sbit =
+ pm.test_lbg_gamma_composition = 0;
+
+# ifdef PNG_WRITE_tRNS_SUPPORTED
+ else if (strcmp(*argv, "--tRNS") == 0)
+ pm.test_tRNS = 1;
+# endif
+
+ else if (strcmp(*argv, "--notRNS") == 0)
+ pm.test_tRNS = 0;
else if (strcmp(*argv, "--more-gammas") == 0)
pm.ngamma_tests = 3U;
@@ -11102,7 +11339,7 @@
Try
{
/* Make useful base images */
- make_transform_images(&pm.this);
+ make_transform_images(&pm);
/* Perform the standard and gamma tests. */
if (pm.test_standard)
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