1 /* Copyright 2015 The TensorFlow Authors. All Rights Reserved. 2 3 Licensed under the Apache License, Version 2.0 (the "License"); 4 you may not use this file except in compliance with the License. 5 You may obtain a copy of the License at 6 7 http://www.apache.org/licenses/LICENSE-2.0 8 9 Unless required by applicable law or agreed to in writing, software 10 distributed under the License is distributed on an "AS IS" BASIS, 11 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 See the License for the specific language governing permissions and 13 limitations under the License. 14 ==============================================================================*/ 15 16 // This file defines functions to compress and uncompress JPEG files 17 // to and from memory. It provides interfaces for raw images 18 // (data array and size fields). 19 // Direct manipulation of JPEG strings are supplied: Flip, Rotate, Crop.. 20 21 #ifndef TENSORFLOW_LIB_JPEG_JPEG_MEM_H_ 22 #define TENSORFLOW_LIB_JPEG_JPEG_MEM_H_ 23 24 #include <functional> 25 #include <string> 26 27 #include "tensorflow/core/lib/core/stringpiece.h" 28 #include "tensorflow/core/platform/jpeg.h" 29 #include "tensorflow/core/platform/types.h" 30 31 namespace tensorflow { 32 namespace jpeg { 33 34 // Flags for Uncompress 35 struct UncompressFlags { 36 // ratio can be 1, 2, 4, or 8 and represent the denominator for the scaling 37 // factor (eg ratio = 4 means that the resulting image will be at 1/4 original 38 // size in both directions). 39 int ratio = 1; 40 41 // The number of bytes per pixel (1, 3 or 4), or 0 for autodetect. 42 int components = 0; 43 44 // If true, decoder will use a slower but nicer upscaling of the chroma 45 // planes (yuv420/422 only). 46 bool fancy_upscaling = true; 47 48 // If true, will attempt to fill in missing lines of truncated files 49 bool try_recover_truncated_jpeg = false; 50 51 // The minimum required fraction of lines read before the image is accepted. 52 float min_acceptable_fraction = 1.0; 53 54 // The distance in bytes from one scanline to the other. Should be at least 55 // equal to width*components*sizeof(JSAMPLE). If 0 is passed, the stride 56 // used will be this minimal value. 57 int stride = 0; 58 59 // Setting of J_DCT_METHOD enum in jpeglib.h, for choosing which 60 // algorithm to use for DCT/IDCT. 61 // 62 // Setting this has a quality/speed trade-off implication. 63 J_DCT_METHOD dct_method = JDCT_DEFAULT; 64 65 // Settings of crop window before decompression. 66 bool crop = false; 67 // Vertical coordinate of the top-left corner of the result in the input. 68 int crop_x = 0; 69 // Horizontal coordinate of the top-left corner of the result in the input. 70 int crop_y = 0; 71 // Width of the output image. 72 int crop_width = 0; 73 // Height of the output image. 74 int crop_height = 0; 75 }; 76 77 // Uncompress some raw JPEG data given by the pointer srcdata and the length 78 // datasize. 79 // - width and height are the address where to store the size of the 80 // uncompressed image in pixels. May be nullptr. 81 // - components is the address where the number of read components are 82 // stored. This is *output only*: to request a specific number of 83 // components use flags.components. May be nullptr. 84 // - nwarn is the address in which to store the number of warnings. 85 // May be nullptr. 86 // The function returns a pointer to the raw uncompressed data or NULL if 87 // there was an error. The caller of the function is responsible for 88 // freeing the memory (using delete []). 89 uint8* Uncompress(const void* srcdata, int datasize, 90 const UncompressFlags& flags, int* width, int* height, 91 int* components, // Output only: useful with autodetect 92 int64* nwarn); 93 94 // Version of Uncompress that allocates memory via a callback. The callback 95 // arguments are (width, height, components). If the size is known ahead of 96 // time this function can return an existing buffer; passing a callback allows 97 // the buffer to be shaped based on the JPEG header. The caller is responsible 98 // for freeing the memory *even along error paths*. 99 uint8* Uncompress(const void* srcdata, int datasize, 100 const UncompressFlags& flags, int64* nwarn, 101 std::function<uint8*(int, int, int)> allocate_output); 102 103 // Read jpeg header and get image information. Returns true on success. 104 // The width, height, and components points may be null. 105 bool GetImageInfo(const void* srcdata, int datasize, int* width, int* height, 106 int* components); 107 108 // Note: (format & 0xff) = number of components (<=> bytes per pixels) 109 enum Format { 110 FORMAT_GRAYSCALE = 0x001, // 1 byte/pixel 111 FORMAT_RGB = 0x003, // 3 bytes/pixel RGBRGBRGBRGB... 112 FORMAT_RGBA = 0x004, // 4 bytes/pixel RGBARGBARGBARGBA... 113 FORMAT_ABGR = 0x104 // 4 bytes/pixel ABGRABGRABGR... 114 }; 115 116 // Flags for compression 117 struct CompressFlags { 118 // Encoding of the input data for compression 119 Format format; 120 121 // Quality of the compression from 0-100 122 int quality = 95; 123 124 // If true, create a jpeg image that loads progressively 125 bool progressive = false; 126 127 // If true, reduce jpeg size without changing quality (at the cost of CPU/RAM) 128 bool optimize_jpeg_size = false; 129 130 // See http://en.wikipedia.org/wiki/Chroma_subsampling 131 bool chroma_downsampling = true; 132 133 // Resolution 134 int density_unit = 1; // 1 = in, 2 = cm 135 int x_density = 300; 136 int y_density = 300; 137 138 // If not empty, embed this XMP metadata in the image header 139 StringPiece xmp_metadata; 140 141 // The distance in bytes from one scanline to the other. Should be at least 142 // equal to width*components*sizeof(JSAMPLE). If 0 is passed, the stride 143 // used will be this minimal value. 144 int stride = 0; 145 }; 146 147 // Compress some raw image given in srcdata, the data is a 2D array of size 148 // stride*height with one of the formats enumerated above. 149 // The encoded data is returned as a string. 150 // If not empty, XMP metadata can be embedded in the image header 151 // On error, returns the empty string (which is never a valid jpeg). 152 string Compress(const void* srcdata, int width, int height, 153 const CompressFlags& flags); 154 155 // On error, returns false and sets output to empty. 156 bool Compress(const void* srcdata, int width, int height, 157 const CompressFlags& flags, string* output); 158 159 } // namespace jpeg 160 } // namespace tensorflow 161 162 #endif // TENSORFLOW_LIB_JPEG_JPEG_MEM_H_ 163
