78318b30e5
Apply gamma correction to the decoded RGB values. This handles corner cases where the PNG file doesn't have a standard 1/2.2 gamma value. BUG=webp:369 Change-Id: I9907b6e2c458002de7c26d0b9e416278cca33990
341 lines
10 KiB
C
341 lines
10 KiB
C
// Copyright 2012 Google Inc. All Rights Reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the COPYING file in the root of the source
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// tree. An additional intellectual property rights grant can be found
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// in the file PATENTS. All contributing project authors may
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// be found in the AUTHORS file in the root of the source tree.
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// -----------------------------------------------------------------------------
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//
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// PNG decode.
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#include "./pngdec.h"
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#ifdef HAVE_CONFIG_H
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#include "webp/config.h"
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#endif
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#include <stdio.h>
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#ifdef WEBP_HAVE_PNG
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#include <png.h>
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#include <setjmp.h> // note: this must be included *after* png.h
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#include <stdlib.h>
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#include <string.h>
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#include "webp/encode.h"
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#include "./imageio_util.h"
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#include "./metadata.h"
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static void PNGAPI error_function(png_structp png, png_const_charp error) {
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if (error != NULL) fprintf(stderr, "libpng error: %s\n", error);
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longjmp(png_jmpbuf(png), 1);
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}
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// Converts the NULL terminated 'hexstring' which contains 2-byte character
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// representations of hex values to raw data.
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// 'hexstring' may contain values consisting of [A-F][a-f][0-9] in pairs,
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// e.g., 7af2..., separated by any number of newlines.
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// 'expected_length' is the anticipated processed size.
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// On success the raw buffer is returned with its length equivalent to
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// 'expected_length'. NULL is returned if the processed length is less than
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// 'expected_length' or any character aside from those above is encountered.
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// The returned buffer must be freed by the caller.
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static uint8_t* HexStringToBytes(const char* hexstring,
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size_t expected_length) {
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const char* src = hexstring;
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size_t actual_length = 0;
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uint8_t* const raw_data = (uint8_t*)malloc(expected_length);
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uint8_t* dst;
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if (raw_data == NULL) return NULL;
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for (dst = raw_data; actual_length < expected_length && *src != '\0'; ++src) {
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char* end;
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char val[3];
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if (*src == '\n') continue;
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val[0] = *src++;
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val[1] = *src;
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val[2] = '\0';
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*dst++ = (uint8_t)strtol(val, &end, 16);
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if (end != val + 2) break;
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++actual_length;
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}
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if (actual_length != expected_length) {
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free(raw_data);
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return NULL;
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}
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return raw_data;
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}
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static int ProcessRawProfile(const char* profile, size_t profile_len,
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MetadataPayload* const payload) {
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const char* src = profile;
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char* end;
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int expected_length;
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if (profile == NULL || profile_len == 0) return 0;
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// ImageMagick formats 'raw profiles' as
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// '\n<name>\n<length>(%8lu)\n<hex payload>\n'.
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if (*src != '\n') {
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fprintf(stderr, "Malformed raw profile, expected '\\n' got '\\x%.2X'\n",
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*src);
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return 0;
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}
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++src;
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// skip the profile name and extract the length.
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while (*src != '\0' && *src++ != '\n') {}
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expected_length = (int)strtol(src, &end, 10);
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if (*end != '\n') {
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fprintf(stderr, "Malformed raw profile, expected '\\n' got '\\x%.2X'\n",
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*end);
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return 0;
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}
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++end;
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// 'end' now points to the profile payload.
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payload->bytes = HexStringToBytes(end, expected_length);
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if (payload->bytes == NULL) return 0;
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payload->size = expected_length;
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return 1;
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}
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static const struct {
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const char* name;
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int (*process)(const char* profile, size_t profile_len,
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MetadataPayload* const payload);
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size_t storage_offset;
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} kPNGMetadataMap[] = {
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// http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/PNG.html#TextualData
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// See also: ExifTool on CPAN.
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{ "Raw profile type exif", ProcessRawProfile, METADATA_OFFSET(exif) },
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{ "Raw profile type xmp", ProcessRawProfile, METADATA_OFFSET(xmp) },
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// Exiftool puts exif data in APP1 chunk, too.
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{ "Raw profile type APP1", ProcessRawProfile, METADATA_OFFSET(exif) },
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// XMP Specification Part 3, Section 3 #PNG
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{ "XML:com.adobe.xmp", MetadataCopy, METADATA_OFFSET(xmp) },
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{ NULL, NULL, 0 },
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};
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// Looks for metadata at both the beginning and end of the PNG file, giving
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// preference to the head.
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// Returns true on success. The caller must use MetadataFree() on 'metadata' in
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// all cases.
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static int ExtractMetadataFromPNG(png_structp png,
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png_infop const head_info,
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png_infop const end_info,
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Metadata* const metadata) {
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int p;
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for (p = 0; p < 2; ++p) {
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png_infop const info = (p == 0) ? head_info : end_info;
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png_textp text = NULL;
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const png_uint_32 num = png_get_text(png, info, &text, NULL);
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png_uint_32 i;
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// Look for EXIF / XMP metadata.
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for (i = 0; i < num; ++i, ++text) {
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int j;
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for (j = 0; kPNGMetadataMap[j].name != NULL; ++j) {
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if (!strcmp(text->key, kPNGMetadataMap[j].name)) {
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MetadataPayload* const payload =
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(MetadataPayload*)((uint8_t*)metadata +
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kPNGMetadataMap[j].storage_offset);
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png_size_t text_length;
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switch (text->compression) {
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#ifdef PNG_iTXt_SUPPORTED
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case PNG_ITXT_COMPRESSION_NONE:
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case PNG_ITXT_COMPRESSION_zTXt:
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text_length = text->itxt_length;
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break;
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#endif
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case PNG_TEXT_COMPRESSION_NONE:
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case PNG_TEXT_COMPRESSION_zTXt:
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default:
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text_length = text->text_length;
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break;
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}
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if (payload->bytes != NULL) {
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fprintf(stderr, "Ignoring additional '%s'\n", text->key);
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} else if (!kPNGMetadataMap[j].process(text->text, text_length,
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payload)) {
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fprintf(stderr, "Failed to process: '%s'\n", text->key);
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return 0;
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}
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break;
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}
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}
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}
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// Look for an ICC profile.
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{
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png_charp name;
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int comp_type;
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#if ((PNG_LIBPNG_VER_MAJOR << 8) | PNG_LIBPNG_VER_MINOR << 0) < \
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((1 << 8) | (5 << 0))
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png_charp profile;
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#else // >= libpng 1.5.0
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png_bytep profile;
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#endif
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png_uint_32 len;
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if (png_get_iCCP(png, info,
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&name, &comp_type, &profile, &len) == PNG_INFO_iCCP) {
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if (!MetadataCopy((const char*)profile, len, &metadata->iccp)) return 0;
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}
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}
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}
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return 1;
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}
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typedef struct {
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const uint8_t* data;
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size_t data_size;
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png_size_t offset;
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} PNGReadContext;
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static void ReadFunc(png_structp png_ptr, png_bytep data, png_size_t length) {
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PNGReadContext* const ctx = (PNGReadContext*)png_get_io_ptr(png_ptr);
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if (ctx->data_size - ctx->offset < length) {
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png_error(png_ptr, "ReadFunc: invalid read length (overflow)!");
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}
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memcpy(data, ctx->data + ctx->offset, length);
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ctx->offset += length;
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}
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int ReadPNG(const uint8_t* const data, size_t data_size,
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struct WebPPicture* const pic,
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int keep_alpha, struct Metadata* const metadata) {
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volatile png_structp png = NULL;
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volatile png_infop info = NULL;
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volatile png_infop end_info = NULL;
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PNGReadContext context = { NULL, 0, 0 };
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int color_type, bit_depth, interlaced;
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int has_alpha;
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int num_passes;
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int p;
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volatile int ok = 0;
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png_uint_32 width, height, y;
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int64_t stride;
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uint8_t* volatile rgb = NULL;
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if (data == NULL || data_size == 0 || pic == NULL) return 0;
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context.data = data;
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context.data_size = data_size;
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png = png_create_read_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);
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if (png == NULL) goto End;
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png_set_error_fn(png, 0, error_function, NULL);
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if (setjmp(png_jmpbuf(png))) {
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Error:
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MetadataFree(metadata);
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goto End;
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}
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info = png_create_info_struct(png);
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if (info == NULL) goto Error;
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end_info = png_create_info_struct(png);
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if (end_info == NULL) goto Error;
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png_set_read_fn(png, &context, ReadFunc);
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png_read_info(png, info);
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if (!png_get_IHDR(png, info,
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&width, &height, &bit_depth, &color_type, &interlaced,
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NULL, NULL)) goto Error;
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png_set_strip_16(png);
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png_set_packing(png);
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if (color_type == PNG_COLOR_TYPE_PALETTE) {
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png_set_palette_to_rgb(png);
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}
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if (color_type == PNG_COLOR_TYPE_GRAY ||
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color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
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if (bit_depth < 8) {
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png_set_expand_gray_1_2_4_to_8(png);
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}
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png_set_gray_to_rgb(png);
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}
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if (png_get_valid(png, info, PNG_INFO_tRNS)) {
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png_set_tRNS_to_alpha(png);
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has_alpha = 1;
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} else {
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has_alpha = !!(color_type & PNG_COLOR_MASK_ALPHA);
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}
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// Apply gamma correction if needed.
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{
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double image_gamma = 1 / 2.2, screen_gamma = 2.2;
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int srgb_intent;
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if (png_get_sRGB(png, info, &srgb_intent) ||
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png_get_gAMA(png, info, &image_gamma)) {
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png_set_gamma(png, screen_gamma, image_gamma);
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}
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}
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if (!keep_alpha) {
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png_set_strip_alpha(png);
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has_alpha = 0;
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}
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num_passes = png_set_interlace_handling(png);
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png_read_update_info(png, info);
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stride = (int64_t)(has_alpha ? 4 : 3) * width * sizeof(*rgb);
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if (stride != (int)stride ||
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!ImgIoUtilCheckSizeArgumentsOverflow(stride, height)) {
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goto Error;
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}
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rgb = (uint8_t*)malloc((size_t)stride * height);
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if (rgb == NULL) goto Error;
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for (p = 0; p < num_passes; ++p) {
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png_bytep row = rgb;
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for (y = 0; y < height; ++y) {
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png_read_rows(png, &row, NULL, 1);
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row += stride;
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}
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}
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png_read_end(png, end_info);
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if (metadata != NULL &&
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!ExtractMetadataFromPNG(png, info, end_info, metadata)) {
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fprintf(stderr, "Error extracting PNG metadata!\n");
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goto Error;
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}
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pic->width = (int)width;
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pic->height = (int)height;
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ok = has_alpha ? WebPPictureImportRGBA(pic, rgb, (int)stride)
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: WebPPictureImportRGB(pic, rgb, (int)stride);
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if (!ok) {
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goto Error;
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}
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End:
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if (png != NULL) {
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png_destroy_read_struct((png_structpp)&png,
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(png_infopp)&info, (png_infopp)&end_info);
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}
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free(rgb);
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return ok;
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}
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#else // !WEBP_HAVE_PNG
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int ReadPNG(const uint8_t* const data, size_t data_size,
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struct WebPPicture* const pic,
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int keep_alpha, struct Metadata* const metadata) {
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(void)data;
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(void)data_size;
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(void)pic;
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(void)keep_alpha;
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(void)metadata;
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fprintf(stderr, "PNG support not compiled. Please install the libpng "
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"development package before building.\n");
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return 0;
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}
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#endif // WEBP_HAVE_PNG
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// -----------------------------------------------------------------------------
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