--- /dev/null
+commit a21a5b22c10b900d44d40fe30a203302b2a67f8b
+Author: John Bowler <jbowler@acm.org>
+Date: Mon Mar 30 21:38:31 2015 -0500
+
+ [libpng16] Fixed rgb_to_gray checks and added tRNS checks to pngvalid.c
+
+#diff --git a/ANNOUNCE b/ANNOUNCE
+#index 73fadac..7e6c842 100644
+#--- a/ANNOUNCE
+#+++ b/ANNOUNCE
+#@@ -1,4 +1,4 @@
+#-Libpng 1.6.18beta01 - March 27, 2015
+#+Libpng 1.6.18beta01 - March 31, 2015
+#
+# This is not intended to be a public release. It will be replaced
+# within a few weeks by a public version or by another test version.
+#@@ -25,10 +25,11 @@ Other information:
+#
+# Changes since the last public release (1.6.17):
+#
+#-Version 1.6.18beta01 [March 27, 2015]
+#+Version 1.6.18beta01 [March 31, 2015]
+# Removed PNG_SET_CHUNK_[CACHE|MALLOC]_LIMIT_SUPPORTED macros. They
+# have been combined with PNG_SET_USER_LIMITS_SUPPORTED (resolves
+# bug report by Andrew Church).
+#+ Fixed rgb_to_gray checks and added tRNS checks to pngvalid.c
+#
+# Send comments/corrections/commendations to png-mng-implement at lists.sf.net
+# (subscription required; visit
+#diff --git a/CHANGES b/CHANGES
+#index fe07211..35b5979 100644
+#--- a/CHANGES
+#+++ b/CHANGES
+#@@ -5205,10 +5205,11 @@ Version 1.6.17rc06 [March 23, 2015]
+# Version 1.6.17 [March 26, 2015]
+# No changes.
+#
+#-Version 1.6.18beta01 [March 27, 2015]
+#+Version 1.6.18beta01 [March 31, 2015]
+# Removed PNG_SET_CHUNK_[CACHE|MALLOC]_LIMIT_SUPPORTED macros. They
+# have been combined with PNG_SET_USER_LIMITS_SUPPORTED (resolves
+# bug report by Andrew Church).
+#+ Fixed rgb_to_gray checks and added tRNS checks to pngvalid.c
+#
+# Send comments/corrections/commendations to png-mng-implement at lists.sf.net
+# (subscription required; visit
+diff --git a/autogen.sh b/autogen.sh
+index 9af34bd..702a0c1 100755
+--- a/autogen.sh
++++ b/autogen.sh
+@@ -73,8 +73,9 @@ done
+ # present bad things are happening.
+ #
+ # The autotools generated files:
+-libpng_autotools_files="Makefile.in aclocal.m4 config.guess config.h.in\
+- config.sub configure depcomp install-sh ltmain.sh missing test-driver"
++libpng_autotools_files="Makefile.in aclocal.m4 config.guess config.h.in
++ config.h.in~ config.sub configure depcomp install-sh ltmain.sh missing\
++ test-driver"
+ #
+ # Files generated by versions of configue >2.68 or automake >1.13 (i.e. later
+ # versions than those required by configure.ac):
+diff --git a/contrib/libtests/pngvalid.c b/contrib/libtests/pngvalid.c
+index 8852f87..60f23dc 100644
+--- a/contrib/libtests/pngvalid.c
++++ b/contrib/libtests/pngvalid.c
+@@ -258,7 +258,7 @@ make_four_random_bytes(png_uint_32* seed, png_bytep bytes)
+ 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 @@ randomize(void *pv, size_t size)
+ }
+
+ #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 @@ random_choice(void)
+ /* 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 @@ standard_name(char *buffer, size_t bufsize, size_t pos, png_byte colour_type,
+ 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 @@ standard_name_from_id(char *buffer, size_t bufsize, size_t pos, png_uint_32 id)
+
+ 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)
+- *bit_depth = 8;
+- else
++ if (low_depth_gray)
+ *bit_depth = 1;
++ else
++ *bit_depth = 8;
+ *palette_number = 0;
+ return 1;
+ }
+
+- if (*colour_type == 3)
++ if (*colour_type < 4/*no alpha channel*/)
+ {
+- /* Add multiple palettes for colour type 3. */
+- if (++*palette_number < PALETTE_COUNT(*bit_depth))
++ /* 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 @@ typedef struct png_modifier
+
+ /* 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
+@@ -1990,6 +2005,16 @@ typedef struct png_modifier
+ 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 */
+
+ /* Buffer information, the buffer size limits the size of the chunks that can
+@@ -2042,6 +2067,11 @@ modifier_init(png_modifier *pm)
+ 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 @@ modifier_init(png_modifier *pm)
+ 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 @@ init_standard_palette(png_store *ps, png_structp pp, png_infop pi, int npalette,
+ }
+ }
+
++#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 @@ make_transform_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type,
+ 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 @@ make_transform_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type,
+ }
+
+ 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.
++ * 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, 0))
++ while (next_format(&colour_type, &bit_depth, &palette_number, 1, 1))
+ {
+ int interlace_type;
+
+@@ -3621,7 +3701,7 @@ make_transform_images(png_store *ps)
+
+ 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 @@ typedef struct standard_display
+ 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 @@ standard_info_part1(standard_display *dp, png_structp pp, png_infop pi)
+ 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 @@ image_pixel_add_alpha(image_pixel *this, PNG_CONST standard_display *display)
+ 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 @@ image_pixel_add_alpha(image_pixel *this, PNG_CONST standard_display *display)
+ 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 @@ transform_info_imp(transform_display *dp, png_structp pp, png_infop pi)
+ /* 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 @@ image_transform_png_set_tRNS_to_alpha_set(PNG_CONST image_transform *this,
+ 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 @@ image_transform_png_set_gray_to_rgb_set(PNG_CONST image_transform *this,
+ 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 @@ image_transform_png_set_expand_set(PNG_CONST image_transform *this,
+ 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 @@ image_transform_png_set_expand_gray_1_2_4_to_8_set(
+ 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 @@ image_transform_png_set_expand_16_set(PNG_CONST image_transform *this,
+ 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 @@ image_transform_png_set_rgb_to_gray_ini(PNG_CONST image_transform *this,
+ * 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 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
+ 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 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
+ * 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;
++ PNG_CONST double abse = .5/(sample_depth == 16 ? 65535 : 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.
++ /* 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 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
+
+ {
+ PNG_CONST int do_round = data.gamma != 1 || calc_depth == 16;
+- PNG_CONST double ce = 1. / 32768;
++ PNG_CONST double ce = 2. / 32768;
+
+- graylo = digitize(rlo * (data.red_coefficient-ce) +
++ 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;
++ blo * (data.blue_coefficient-ce), calc_depth, do_round);
++ if (graylo > gray) /* always accept the right answer */
++ graylo = gray;
+
+- grayhi = digitize(rhi * (data.red_coefficient+ce) +
++ 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. */
+@@ -7205,11 +7325,25 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
+ {
+ 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.
+ *
+ * If r==g==b because there is no overall gamma correction libpng
+@@ -7260,16 +7394,28 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
+ {
+ /* 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 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
+ * 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 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
+ }
+
+ 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 @@ image_transform_png_set_background_set(PNG_CONST image_transform *this,
+
+ else
+ {
++ if (that->this.has_tRNS)
++ that->this.is_transparent = 1;
++
+ bit_depth = that->this.bit_depth;
+ expand = 1;
+ }
+@@ -7506,14 +7655,14 @@ image_transform_png_set_background_mod(PNG_CONST image_transform *this,
+ /* 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 @@ perform_transform_test(png_modifier *pm)
+ 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 @@ init_validate_info(validate_info *vi, gamma_display *dp, png_const_structp pp,
+ 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 @@ init_validate_info(validate_info *vi, gamma_display *dp, png_const_structp pp,
+ 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 @@ gamma_image_validate(gamma_display *dp, png_const_structp pp,
+ 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 @@ gamma_image_validate(gamma_display *dp, png_const_structp pp,
+
+ 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 @@ gamma_image_validate(gamma_display *dp, png_const_structp pp,
+ /* 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 :
+@@ -9436,6 +9590,35 @@ gamma_image_validate(gamma_display *dp, png_const_structp pp,
+ }
+ }
+
++ 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;
++ }
++ }
++
+ /* Handle grayscale or RGB components. */
+ if ((in_ct & PNG_COLOR_MASK_COLOR) == 0) /* grayscale */
+ (void)gamma_component_validate("gray", &vi,
+@@ -9545,7 +9728,7 @@ gamma_test(png_modifier *pmIn, PNG_CONST png_byte colour_typeIn,
+
+ 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 @@ perform_gamma_threshold_tests(png_modifier *pm)
+ /* 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!
++ *
++ * CHANGED: now test two palettes and, as a side effect, images with and
++ * without tRNS.
+ */
+- while (next_format(&colour_type, &bit_depth, &palette_number, 1/*gamma*/))
+- if (palette_number == 0)
++ 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 @@ static void perform_gamma_transform_tests(png_modifier *pm)
+ 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 @@ static void perform_gamma_sbit_tests(png_modifier *pm)
+ 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 @@ static void gamma_composition_test(png_modifier *pm,
+ }
+
+ 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 @@ perform_gamma_composition_tests(png_modifier *pm, int do_background,
+
+ /* 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 @@ int main(int argc, char **argv)
+ 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 @@ int main(int argc, char **argv)
+ 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;
+ }
+
+@@ -10912,6 +11131,24 @@ int main(int argc, char **argv)
+ 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 @@ int main(int argc, char **argv)
+ Try
+ {
+ /* Make useful base images */
+- make_transform_images(&pm.this);
++ make_transform_images(&pm);
+
+ /* Perform the standard and gamma tests. */
+ if (pm.test_standard)
projects / packages / libpng.git / commitdiff