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Fixed point APIs are now supported throughout (no missing APIs).
  Internal fixed point arithmetic support exists for all internal floating
    point operations.
  sCAL validates the floating point strings it is passed.
  Safe, albeit rudimentary, Watcom support is provided by PNG_API_RULE==2
  Two new APIs exist to get the number of passes without turning on the
    PNG_INTERLACE transform and to get the number of rows in the current
    pass.
  A new test program, pngvalid.c, validates the gamma code.
  Errors in the 16 bit gamma correction (overflows) have been corrected.
  cHRM chunk testing is done consistently (previously the floating point
    API bypassed it, because the test really didn't work on FP, now the test
    is performed on the actual values to be stored in the PNG file so it
    works in the FP case too.)
  Most floating point APIs now simply call the fixed point APIs after
    converting the values to the fixed point form used in the PNG file.
  The standard headers no longer include zlib.h, which is currently only
    required for pngstruct.h and can therefore be internal.
  (Patches by John Bowler)
This commit is contained in:
Glenn Randers-Pehrson
2010-07-29 17:39:14 -05:00
parent d7aa6aa916
commit 31aee0d0c0
44 changed files with 4989 additions and 1723 deletions
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470
pngrtran.c
View File

@@ -1,7 +1,7 @@
/* pngrtran.c - transforms the data in a row for PNG readers
*
* Last changed in libpng 1.5.0 [July 24, 2010]
* Last changed in libpng 1.5.0 [July 29, 2010]
* Copyright (c) 1998-2010 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -88,15 +88,14 @@ png_set_crc_action(png_structp png_ptr, int crit_action, int ancil_action)
}
}
#if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
defined(PNG_FLOATING_POINT_SUPPORTED)
#ifdef PNG_READ_BACKGROUND_SUPPORTED
/* Handle alpha and tRNS via a background color */
void PNGAPI
png_set_background(png_structp png_ptr,
void PNGFAPI
png_set_background_fixed(png_structp png_ptr,
png_color_16p background_color, int background_gamma_code,
int need_expand, double background_gamma)
int need_expand, png_fixed_point background_gamma)
{
png_debug(1, "in png_set_background");
png_debug(1, "in png_set_background_fixed");
if (png_ptr == NULL)
return;
@@ -110,11 +109,22 @@ png_set_background(png_structp png_ptr,
png_ptr->transformations |= PNG_BACKGROUND;
png_memcpy(&(png_ptr->background), background_color,
png_sizeof(png_color_16));
png_ptr->background_gamma = (float)background_gamma;
png_ptr->background_gamma = background_gamma;
png_ptr->background_gamma_type = (png_byte)(background_gamma_code);
png_ptr->transformations |= (need_expand ? PNG_BACKGROUND_EXPAND : 0);
}
#endif
# ifdef PNG_FLOATING_POINT_SUPPORTED
void PNGAPI
png_set_background(png_structp png_ptr,
png_color_16p background_color, int background_gamma_code,
int need_expand, double background_gamma)
{
png_set_background_fixed(png_ptr, background_color, background_gamma_code,
need_expand, png_fixed(png_ptr, background_gamma, "png_set_background"));
}
# endif /* FLOATING_POINT */
#endif /* READ_BACKGROUND */
#ifdef PNG_READ_16_TO_8_SUPPORTED
/* Strip 16 bit depth files to 8 bit depth */
@@ -549,7 +559,7 @@ png_set_quantize(png_structp png_ptr, png_colorp palette,
}
#endif /* PNG_READ_QUANTIZE_SUPPORTED */
#if defined(PNG_READ_GAMMA_SUPPORTED) && defined(PNG_FLOATING_POINT_SUPPORTED)
#ifdef PNG_READ_GAMMA_SUPPORTED
/* Transform the image from the file_gamma to the screen_gamma. We
* only do transformations on images where the file_gamma and screen_gamma
* are not close reciprocals, otherwise it slows things down slightly, and
@@ -559,22 +569,48 @@ png_set_quantize(png_structp png_ptr, png_colorp palette,
* are present in the tRNS array for palette images. We can't do it here
* because we don't necessarily have the tRNS chunk yet.
*/
void PNGAPI
png_set_gamma(png_structp png_ptr, double scrn_gamma, double file_gamma)
static int /* PRIVATE */
png_gamma_threshold(png_fixed_point scrn_gamma, png_fixed_point file_gamma)
{
png_debug(1, "in png_set_gamma");
/* PNG_GAMMA_THRESHOLD is the threshold for performing gamma
* correction as a difference of the overall transform from 1.0
*
* We want to compare the threshold with s*f - 1, if we get
* overflow here it is because of wacky gamma values so we
* turn on processing anyway.
*/
png_fixed_point gtest;
return !png_muldiv(&gtest, scrn_gamma, file_gamma, PNG_FP_1) ||
png_gamma_significant(gtest);
}
void PNGFAPI
png_set_gamma_fixed(png_structp png_ptr, png_fixed_point scrn_gamma,
png_fixed_point file_gamma)
{
png_debug(1, "in png_set_gamma_fixed");
if (png_ptr == NULL)
return;
if ((fabs(scrn_gamma * file_gamma - 1.0) > PNG_GAMMA_THRESHOLD) ||
(png_ptr->color_type & PNG_COLOR_MASK_ALPHA) ||
(png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) ||
(png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ||
png_gamma_threshold(scrn_gamma, file_gamma))
png_ptr->transformations |= PNG_GAMMA;
png_ptr->gamma = (float)file_gamma;
png_ptr->screen_gamma = (float)scrn_gamma;
png_ptr->gamma = file_gamma;
png_ptr->screen_gamma = scrn_gamma;
}
#endif
# ifdef PNG_FLOATING_POINT_SUPPORTED
void PNGAPI
png_set_gamma(png_structp png_ptr, double scrn_gamma, double file_gamma)
{
png_set_gamma_fixed(png_ptr,
png_fixed(png_ptr, scrn_gamma, "png_set_gamma screen gamma"),
png_fixed(png_ptr, file_gamma, "png_set_gamma file gamma"));
}
# endif /* FLOATING_POINT_SUPPORTED */
#endif /* READ_GAMMA */
#ifdef PNG_READ_EXPAND_SUPPORTED
/* Expand paletted images to RGB, expand grayscale images of
@@ -662,12 +698,7 @@ png_set_gray_to_rgb(png_structp png_ptr)
#endif
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
void
#ifdef PNG_FIXED_POINT_SUPPORTED
PNGAPI
#else
/* PRIVATE */
#endif
void PNGFAPI
png_set_rgb_to_gray_fixed(png_structp png_ptr, int error_action,
png_fixed_point red, png_fixed_point green)
{
@@ -735,15 +766,14 @@ png_set_rgb_to_gray_fixed(png_structp png_ptr, int error_action,
void PNGAPI
png_set_rgb_to_gray(png_structp png_ptr, int error_action, double red,
double green)
double green)
{
int red_fixed = (int)((float)red*100000.0 + 0.5);
int green_fixed = (int)((float)green*100000.0 + 0.5);
if (png_ptr == NULL)
return;
png_set_rgb_to_gray_fixed(png_ptr, error_action, red_fixed, green_fixed);
png_set_rgb_to_gray_fixed(png_ptr, error_action,
png_fixed(png_ptr, red, "rgb to gray red coefficient"),
png_fixed(png_ptr, green, "rgb to gray green coefficient"));
}
#endif /* FLOATING POINT */
@@ -886,7 +916,8 @@ png_init_read_transformations(png_structp png_ptr)
int i, istop;
istop=(int)png_ptr->num_trans;
for (i=0; i<istop; i++)
png_ptr->trans_alpha[i] = (png_byte)(255 - png_ptr->trans_alpha[i]);
png_ptr->trans_alpha[i] = (png_byte)(255 -
png_ptr->trans_alpha[i]);
}
}
#endif
@@ -898,11 +929,10 @@ png_init_read_transformations(png_structp png_ptr)
#if defined(PNG_READ_BACKGROUND_SUPPORTED) && defined(PNG_READ_GAMMA_SUPPORTED)
png_ptr->background_1 = png_ptr->background;
#endif
#if defined(PNG_READ_GAMMA_SUPPORTED) && defined(PNG_FLOATING_POINT_SUPPORTED)
#ifdef PNG_READ_GAMMA_SUPPORTED
if ((color_type == PNG_COLOR_TYPE_PALETTE && png_ptr->num_trans != 0)
&& (fabs(png_ptr->screen_gamma * png_ptr->gamma - 1.0)
< PNG_GAMMA_THRESHOLD))
&& png_gamma_threshold(png_ptr->screen_gamma, png_ptr->gamma))
{
int i, k;
k=0;
@@ -916,7 +946,7 @@ png_init_read_transformations(png_structp png_ptr)
}
if ((png_ptr->transformations & (PNG_GAMMA | PNG_RGB_TO_GRAY)) &&
png_ptr->gamma != 0.0)
png_ptr->gamma != 0)
{
png_build_gamma_table(png_ptr, png_ptr->bit_depth);
@@ -932,6 +962,7 @@ png_init_read_transformations(png_structp png_ptr)
int i;
if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE)
{
back.red = png_ptr->gamma_table[png_ptr->background.red];
back.green = png_ptr->gamma_table[png_ptr->background.green];
back.blue = png_ptr->gamma_table[png_ptr->background.blue];
@@ -942,31 +973,33 @@ png_init_read_transformations(png_structp png_ptr)
}
else
{
double g, gs;
png_fixed_point g, gs;
switch (png_ptr->background_gamma_type)
{
case PNG_BACKGROUND_GAMMA_SCREEN:
g = (png_ptr->screen_gamma);
gs = 1.0;
gs = PNG_FP_1;
break;
case PNG_BACKGROUND_GAMMA_FILE:
g = 1.0 / (png_ptr->gamma);
gs = 1.0 / (png_ptr->gamma * png_ptr->screen_gamma);
g = png_reciprocal(png_ptr->gamma);
gs = png_reciprocal2(png_ptr->gamma,
png_ptr->screen_gamma);
break;
case PNG_BACKGROUND_GAMMA_UNIQUE:
g = 1.0 / (png_ptr->background_gamma);
gs = 1.0 / (png_ptr->background_gamma *
png_ptr->screen_gamma);
g = png_reciprocal(png_ptr->background_gamma);
gs = png_reciprocal2(png_ptr->background_gamma,
png_ptr->screen_gamma);
break;
default:
g = 1.0; /* back_1 */
gs = 1.0; /* back */
g = PNG_FP_1; /* back_1 */
gs = PNG_FP_1; /* back */
break;
}
if ( fabs(gs - 1.0) < PNG_GAMMA_THRESHOLD)
if ( png_gamma_significant(gs) )
{
back.red = (png_byte)png_ptr->background.red;
back.green = (png_byte)png_ptr->background.green;
@@ -975,24 +1008,18 @@ png_init_read_transformations(png_structp png_ptr)
else
{
back.red = (png_byte)(pow(
(double)png_ptr->background.red/255.0, gs) * 255.0 + .5);
back.green = (png_byte)(pow(
(double)png_ptr->background.green/255.0, gs) * 255.0
+ .5);
back.blue = (png_byte)(pow(
(double)png_ptr->background.blue/255.0, gs) * 255.0
+ .5);
back.red = png_gamma_8bit_correct(png_ptr->background.red,
gs);
back.green = png_gamma_8bit_correct(png_ptr->background.green,
gs);
back.blue = png_gamma_8bit_correct(png_ptr->background.blue,
gs);
}
back_1.red = (png_byte)(pow(
(double)png_ptr->background.red/255.0, g) * 255.0 + .5);
back_1.green = (png_byte)(pow(
(double)png_ptr->background.green/255.0, g) * 255.0 + .5);
back_1.blue = (png_byte)(pow(
(double)png_ptr->background.blue/255.0, g) * 255.0 + .5);
back_1.red = png_gamma_8bit_correct(png_ptr->background.red, g);
back_1.green = png_gamma_8bit_correct(png_ptr->background.green,
g);
back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue,
g);
}
for (i = 0; i < num_palette; i++)
{
@@ -1040,57 +1067,56 @@ png_init_read_transformations(png_structp png_ptr)
else
/* color_type != PNG_COLOR_TYPE_PALETTE */
{
double m = (double)(((png_uint_32)1 << png_ptr->bit_depth) - 1);
double g = 1.0;
double gs = 1.0;
png_fixed_point g = PNG_FP_1;
png_fixed_point gs = PNG_FP_1;
switch (png_ptr->background_gamma_type)
{
case PNG_BACKGROUND_GAMMA_SCREEN:
g = (png_ptr->screen_gamma);
gs = 1.0;
g = png_ptr->screen_gamma;
/* gs = PNG_FP_1; */
break;
case PNG_BACKGROUND_GAMMA_FILE:
g = 1.0 / (png_ptr->gamma);
gs = 1.0 / (png_ptr->gamma * png_ptr->screen_gamma);
g = png_reciprocal(png_ptr->gamma);
gs = png_reciprocal2(png_ptr->gamma, png_ptr->screen_gamma);
break;
case PNG_BACKGROUND_GAMMA_UNIQUE:
g = 1.0 / (png_ptr->background_gamma);
gs = 1.0 / (png_ptr->background_gamma *
png_ptr->screen_gamma);
g = png_reciprocal(png_ptr->background_gamma);
gs = png_reciprocal2(png_ptr->background_gamma,
png_ptr->screen_gamma);
break;
}
png_ptr->background_1.gray = (png_uint_16)(pow(
(double)png_ptr->background.gray / m, g) * m + .5);
png_ptr->background_1.gray = png_gamma_correct(png_ptr,
png_ptr->background.gray, g);
png_ptr->background.gray = (png_uint_16)(pow(
(double)png_ptr->background.gray / m, gs) * m + .5);
png_ptr->background.gray = png_gamma_correct(png_ptr,
png_ptr->background.gray, gs);
if ((png_ptr->background.red != png_ptr->background.green) ||
(png_ptr->background.red != png_ptr->background.blue) ||
(png_ptr->background.red != png_ptr->background.gray))
{
/* RGB or RGBA with color background */
png_ptr->background_1.red = (png_uint_16)(pow(
(double)png_ptr->background.red / m, g) * m + .5);
png_ptr->background_1.red = png_gamma_correct(png_ptr,
png_ptr->background.red, g);
png_ptr->background_1.green = (png_uint_16)(pow(
(double)png_ptr->background.green / m, g) * m + .5);
png_ptr->background_1.green = png_gamma_correct(png_ptr,
png_ptr->background.green, g);
png_ptr->background_1.blue = (png_uint_16)(pow(
(double)png_ptr->background.blue / m, g) * m + .5);
png_ptr->background_1.blue = png_gamma_correct(png_ptr,
png_ptr->background.blue, g);
png_ptr->background.red = (png_uint_16)(pow(
(double)png_ptr->background.red / m, gs) * m + .5);
png_ptr->background.red = png_gamma_correct(png_ptr,
png_ptr->background.red, gs);
png_ptr->background.green = (png_uint_16)(pow(
(double)png_ptr->background.green / m, gs) * m + .5);
png_ptr->background.green = png_gamma_correct(png_ptr,
png_ptr->background.green, gs);
png_ptr->background.blue = (png_uint_16)(pow(
(double)png_ptr->background.blue / m, gs) * m + .5);
png_ptr->background.blue = png_gamma_correct(png_ptr,
png_ptr->background.blue, gs);
}
else
@@ -1127,7 +1153,7 @@ png_init_read_transformations(png_structp png_ptr)
#ifdef PNG_READ_BACKGROUND_SUPPORTED
else
#endif
#endif /* PNG_READ_GAMMA_SUPPORTED && PNG_FLOATING_POINT_SUPPORTED */
#endif /* PNG_READ_GAMMA_SUPPORTED */
#ifdef PNG_READ_BACKGROUND_SUPPORTED
/* No GAMMA transformation */
if ((png_ptr->transformations & PNG_BACKGROUND) &&
@@ -1255,12 +1281,7 @@ png_read_transform_info(png_structp png_ptr, png_infop info_ptr)
#ifdef PNG_READ_GAMMA_SUPPORTED
if (png_ptr->transformations & PNG_GAMMA)
{
#ifdef PNG_FLOATING_POINT_SUPPORTED
info_ptr->gamma = png_ptr->gamma;
#endif
#ifdef PNG_FIXED_POINT_SUPPORTED
info_ptr->int_gamma = png_ptr->int_gamma;
#endif
}
#endif
@@ -4066,267 +4087,6 @@ png_do_quantize(png_row_infop row_info, png_bytep row,
}
#endif /* PNG_READ_QUANTIZE_SUPPORTED */
#ifdef PNG_FLOATING_POINT_SUPPORTED
#ifdef PNG_READ_GAMMA_SUPPORTED
static PNG_CONST int png_gamma_shift[] =
{0x10, 0x21, 0x42, 0x84, 0x110, 0x248, 0x550, 0xff0, 0x00};
/* We build the 8- or 16-bit gamma tables here. Note that for 16-bit
* tables, we don't make a full table if we are reducing to 8-bit in
* the future. Note also how the gamma_16 tables are segmented so that
* we don't need to allocate > 64K chunks for a full 16-bit table.
*
* See the PNG extensions document for an integer algorithm for creating
* the gamma tables. Maybe we will implement that here someday.
*
* We should only reach this point if
*
* the file_gamma is known (i.e., the gAMA or sRGB chunk is present,
* or the application has provided a file_gamma)
*
* AND
* {
* the screen_gamma is known
*
* OR
*
* RGB_to_gray transformation is being performed
* }
*
* AND
* {
* the screen_gamma is different from the reciprocal of the
* file_gamma by more than the specified threshold
*
* OR
*
* a background color has been specified and the file_gamma
* and screen_gamma are not 1.0, within the specified threshold.
* }
*/
void /* PRIVATE */
png_build_gamma_table(png_structp png_ptr, png_byte bit_depth)
{
png_debug(1, "in png_build_gamma_table");
if (bit_depth <= 8)
{
int i;
double g;
if (png_ptr->screen_gamma > .000001)
g = 1.0 / (png_ptr->gamma * png_ptr->screen_gamma);
else
g = 1.0;
png_ptr->gamma_table = (png_bytep)png_malloc(png_ptr,
(png_uint_32)256);
for (i = 0; i < 256; i++)
{
png_ptr->gamma_table[i] = (png_byte)(pow((double)i / 255.0,
g) * 255.0 + .5);
}
#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
if (png_ptr->transformations & ((PNG_BACKGROUND) | PNG_RGB_TO_GRAY))
{
g = 1.0 / (png_ptr->gamma);
png_ptr->gamma_to_1 = (png_bytep)png_malloc(png_ptr,
(png_uint_32)256);
for (i = 0; i < 256; i++)
{
png_ptr->gamma_to_1[i] = (png_byte)(pow((double)i / 255.0,
g) * 255.0 + .5);
}
png_ptr->gamma_from_1 = (png_bytep)png_malloc(png_ptr,
(png_uint_32)256);
if (png_ptr->screen_gamma > 0.000001)
g = 1.0 / png_ptr->screen_gamma;
else
g = png_ptr->gamma; /* Probably doing rgb_to_gray */
for (i = 0; i < 256; i++)
{
png_ptr->gamma_from_1[i] = (png_byte)(pow((double)i / 255.0,
g) * 255.0 + .5);
}
}
#endif /* PNG_READ_BACKGROUND_SUPPORTED || PNG_RGB_TO_GRAY_SUPPORTED */
}
else
{
double g;
int i, j, shift, num;
int sig_bit;
png_uint_32 ig;
if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
{
sig_bit = (int)png_ptr->sig_bit.red;
if ((int)png_ptr->sig_bit.green > sig_bit)
sig_bit = png_ptr->sig_bit.green;
if ((int)png_ptr->sig_bit.blue > sig_bit)
sig_bit = png_ptr->sig_bit.blue;
}
else
{
sig_bit = (int)png_ptr->sig_bit.gray;
}
if (sig_bit > 0)
shift = 16 - sig_bit;
else
shift = 0;
if (png_ptr->transformations & PNG_16_TO_8)
{
if (shift < (16 - PNG_MAX_GAMMA_8))
shift = (16 - PNG_MAX_GAMMA_8);
}
if (shift > 8)
shift = 8;
if (shift < 0)
shift = 0;
png_ptr->gamma_shift = (png_byte)shift;
num = (1 << (8 - shift));
if (png_ptr->screen_gamma > .000001)
g = 1.0 / (png_ptr->gamma * png_ptr->screen_gamma);
else
g = 1.0;
png_ptr->gamma_16_table = (png_uint_16pp)png_calloc(png_ptr,
(png_uint_32)(num * png_sizeof(png_uint_16p)));
if (png_ptr->transformations & (PNG_16_TO_8 | PNG_BACKGROUND))
{
double fin, fout;
png_uint_32 last, max;
for (i = 0; i < num; i++)
{
png_ptr->gamma_16_table[i] = (png_uint_16p)png_malloc(png_ptr,
(png_uint_32)(256 * png_sizeof(png_uint_16)));
}
g = 1.0 / g;
last = 0;
for (i = 0; i < 256; i++)
{
fout = ((double)i + 0.5) / 256.0;
fin = pow(fout, g);
max = (png_uint_32)(fin * (double)((png_uint_32)num << 8));
while (last <= max)
{
png_ptr->gamma_16_table[(int)(last & (0xff >> shift))]
[(int)(last >> (8 - shift))] = (png_uint_16)(
(png_uint_16)i | ((png_uint_16)i << 8));
last++;
}
}
while (last < ((png_uint_32)num << 8))
{
png_ptr->gamma_16_table[(int)(last & (0xff >> shift))]
[(int)(last >> (8 - shift))] = (png_uint_16)65535L;
last++;
}
}
else
{
for (i = 0; i < num; i++)
{
png_ptr->gamma_16_table[i] = (png_uint_16p)png_malloc(png_ptr,
(png_uint_32)(256 * png_sizeof(png_uint_16)));
ig = (((png_uint_32)i * (png_uint_32)png_gamma_shift[shift]) >> 4);
for (j = 0; j < 256; j++)
{
png_ptr->gamma_16_table[i][j] =
(png_uint_16)(pow((double)(ig + ((png_uint_32)j << 8)) /
65535.0, g) * 65535.0 + .5);
}
}
}
#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
if (png_ptr->transformations & (PNG_BACKGROUND | PNG_RGB_TO_GRAY))
{
g = 1.0 / (png_ptr->gamma);
png_ptr->gamma_16_to_1 = (png_uint_16pp)png_calloc(png_ptr,
(png_uint_32)(num * png_sizeof(png_uint_16p )));
for (i = 0; i < num; i++)
{
png_ptr->gamma_16_to_1[i] = (png_uint_16p)png_malloc(png_ptr,
(png_uint_32)(256 * png_sizeof(png_uint_16)));
ig = (((png_uint_32)i *
(png_uint_32)png_gamma_shift[shift]) >> 4);
for (j = 0; j < 256; j++)
{
png_ptr->gamma_16_to_1[i][j] =
(png_uint_16)(pow((double)(ig + ((png_uint_32)j << 8)) /
65535.0, g) * 65535.0 + .5);
}
}
if (png_ptr->screen_gamma > 0.000001)
g = 1.0 / png_ptr->screen_gamma;
else
g = png_ptr->gamma; /* Probably doing rgb_to_gray */
png_ptr->gamma_16_from_1 = (png_uint_16pp)png_calloc(png_ptr,
(png_uint_32)(num * png_sizeof(png_uint_16p)));
for (i = 0; i < num; i++)
{
png_ptr->gamma_16_from_1[i] = (png_uint_16p)png_malloc(png_ptr,
(png_uint_32)(256 * png_sizeof(png_uint_16)));
ig = (((png_uint_32)i *
(png_uint_32)png_gamma_shift[shift]) >> 4);
for (j = 0; j < 256; j++)
{
png_ptr->gamma_16_from_1[i][j] =
(png_uint_16)(pow((double)(ig + ((png_uint_32)j << 8)) /
65535.0, g) * 65535.0 + .5);
}
}
}
#endif /* PNG_READ_BACKGROUND_SUPPORTED || PNG_RGB_TO_GRAY_SUPPORTED */
}
}
#endif
/* To do: install integer version of png_build_gamma_table here */
#endif
#ifdef PNG_MNG_FEATURES_SUPPORTED
/* Undoes intrapixel differencing */
void /* PRIVATE */