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[libpng16] Recognize known sRGB ICC profiles while reading and issue a warning

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about it, if PNG_WARN_IF_iCCP_IS_sRGB_SUPPORTED is defined.
This commit is contained in:
Glenn Randers-Pehrson
2012-03-28 10:58:01 -05:00
parent 13a87d9682
commit 48015617d3
5 changed files with 81 additions and 44 deletions
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111
pngrutil.c
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@@ -1314,6 +1314,67 @@ png_handle_sRGB(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
#endif /* PNG_READ_sRGB_SUPPORTED */
#ifdef PNG_READ_iCCP_SUPPORTED
#ifdef PNG_WARN_IF_iCCP_IS_sRGB_SUPPORTED
int /* PRIVATE */
png_compare_ICC_profile_with_sRGB(png_structrp png_ptr, png_bytep profile,
png_uint_32 length)
{
/* See if it's a known sRGB profile. If it is, return intent;
* if not, return -1.
*/
int
icheck;
/* Known sRGB profiles:
* 0: not a known sRGB profile
* 1: HP-Microsoft sRGB v2 perceptual
* 2: ICC sRGB v4 perceptual
* 3: ICC sRGB v2 perceptual
* no black-compensation
*/
typedef struct png_sRGB_check_struct
{
uLong crc;
uLong adler;
png_uint_32 check_len;
int intent;
} png_sRGB_check;
png_sRGB_check check[3] =
{
{ 0xf29e526dUL, 0x0398f3fcUL, 3144UL, 0 },
{ 0xbbef7812UL, 0x209c35d2UL, 60960UL, 0 },
{ 0x427ebb21UL, 0x4909e5e1UL, 3052UL, 0 }
};
if (png_ptr == NULL)
return -1;
for (icheck = 2; icheck >= 0; icheck--)
{
if (length == check[icheck].check_len)
{
uLong profile_adler = adler32(1, profile, length);
if (profile_adler == (uLong) check[icheck].adler)
{
uLong profile_crc = crc32(0, profile, length);
if (profile_crc == (uLong) check[icheck].crc)
return check[icheck].intent;
else
return -1;
}
}
}
return -1;
}
#endif
void /* PRIVATE */
png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
/* Note: this does not properly handle profiles that are > 64K under DOS */
@@ -1460,23 +1521,10 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
if (size == 0)
{
#ifdef PNG_WARN_IF_iCCP_IS_sRGB_SUPPORTED
int
icheck;
/* Known sRGB profiles:
* 0: not a known sRGB profile
* 1: HP-Microsoft sRGB v2
* 2: ICC sRGB v4 perceptual
* 3: ICC sRGB v2 perceptual
* no black-compensation
*/
png_uint_32 check_crc[4] = {0,
0xf29e526dUL, 0xbbef7812UL,
0x427ebb21UL},
check_len[4] = {0, 3144, 60960,
3052};
intent;
#endif
if (ret != Z_STREAM_END)
png_chunk_warning(png_ptr,
@@ -1495,31 +1543,16 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
if (png_crc_finish(png_ptr, length))
return;
#ifdef PNG_WARN_IF_iCCP_IS_sRGB_SUPPORTED
/* See if it's a known sRGB profile. */
intent =
png_compare_ICC_profile_with_sRGB(
png_ptr, profile, profile_length);
for (icheck=3; icheck > 0; icheck--)
{
if (profile_length == check_len[icheck])
{
uLong profile_crc = crc32(0,
profile, profile_length);
if (profile_crc ==
check_crc[icheck])
{
(void)png_colorspace_set_sRGB(
png_ptr,
&png_ptr->colorspace,
PNG_sRGB_INTENT_PERCEPTUAL,
0);
png_colorspace_sync(png_ptr,
info_ptr);
return;
}
}
}
if (intent >= 0)
png_chunk_warning(png_ptr,
"describes sRGB\n");
#endif
/* Set the gAMA and cHRM information */
png_icc_set_gAMA_and_cHRM(png_ptr,