Differences

This shows you the differences between two versions of the page.

--- images:jpg_to_raw_pixel_buffer [2017/01/17 14:27] – created peter
+++ images:jpg_to_raw_pixel_buffer [2019/11/29 16:28] (current) – removed peter
@@ Line 1: / Line 1: @@
-====== Images - JPG to raw pixel buffer ======
-<code cpp>
-// NanoJPEG -- KeyJ's Tiny Baseline JPEG Decoder
-// version 1.3.5 (2016-11-14)
-// Copyright (c) 2009-2016 Martin J. Fiedler <martin.fiedler@gmx.net>
-// published under the terms of the MIT license
-//
-// Permission is hereby granted, free of charge, to any person obtaining a copy
-// of this software and associated documentation files (the "Software"), to
-// deal in the Software without restriction, including without limitation the
-// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
-// sell copies of the Software, and to permit persons to whom the Software is
-// furnished to do so, subject to the following conditions:
-//
-// The above copyright notice and this permission notice shall be included in
-// all copies or substantial portions of the Software.
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
-// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
-// DEALINGS IN THE SOFTWARE.
-///////////////////////////////////////////////////////////////////////////////
-// DOCUMENTATION SECTION                                                     //
-// read this if you want to know what this is all about                      //
-///////////////////////////////////////////////////////////////////////////////
-// INTRODUCTION
-// ============
-//
-// This is a minimal decoder for baseline JPEG images. It accepts memory dumps
-// of JPEG files as input and generates either 8-bit grayscale or packed 24-bit
-// RGB images as output. It does not parse JFIF or Exif headers; all JPEG files
-// are assumed to be either grayscale or YCbCr. CMYK or other color spaces are
-// not supported. All YCbCr subsampling schemes with power-of-two ratios are
-// supported, as are restart intervals. Progressive or lossless JPEG is not
-// supported.
-// Summed up, NanoJPEG should be able to decode all images from digital cameras
-// and most common forms of other non-progressive JPEG images.
-// The decoder is not optimized for speed, it's optimized for simplicity and
-// small code. Image quality should be at a reasonable level. A bicubic chroma
-// upsampling filter ensures that subsampled YCbCr images are rendered in
-// decent quality. The decoder is not meant to deal with broken JPEG files in
-// a graceful manner; if anything is wrong with the bitstream, decoding will
-// simply fail.
-// The code should work with every modern C compiler without problems and
-// should not emit any warnings. It uses only (at least) 32-bit integer
-// arithmetic and is supposed to be endianness independent and 64-bit clean.
-// However, it is not thread-safe.
-// COMPILE-TIME CONFIGURATION
-// ==========================
-//
-// The following aspects of NanoJPEG can be controlled with preprocessor
-// defines:
-//
-// _NJ_EXAMPLE_PROGRAM     = Compile a main() function with an example
-//                           program.
-// _NJ_INCLUDE_HEADER_ONLY = Don't compile anything, just act as a header
-//                           file for NanoJPEG. Example:
-//                               #define _NJ_INCLUDE_HEADER_ONLY
-//                               #include "nanojpeg.c"
-//                               int main(void) {
-//                                   njInit();
-//                                   // your code here
-//                                   njDone();
-//                               }
-// NJ_USE_LIBC=1           = Use the malloc(), free(), memset() and memcpy()
-//                           functions from the standard C library (default).
-// NJ_USE_LIBC=0           = Don't use the standard C library. In this mode,
-//                           external functions njAlloc(), njFreeMem(),
-//                           njFillMem() and njCopyMem() need to be defined
-//                           and implemented somewhere.
-// NJ_USE_WIN32=0          = Normal mode (default).
-// NJ_USE_WIN32=1          = If compiling with MSVC for Win32 and
-//                           NJ_USE_LIBC=0, NanoJPEG will use its own
-//                           implementations of the required C library
-//                           functions (default if compiling with MSVC and
-//                           NJ_USE_LIBC=0).
-// NJ_CHROMA_FILTER=1      = Use the bicubic chroma upsampling filter
-//                           (default).
-// NJ_CHROMA_FILTER=0      = Use simple pixel repetition for chroma upsampling
-//                           (bad quality, but faster and less code).
-// API
-// ===
-//
-// For API documentation, read the "header section" below.
-// EXAMPLE
-// =======
-//
-// A few pages below, you can find an example program that uses NanoJPEG to
-// convert JPEG files into PGM or PPM. To compile it, use something like
-//     gcc -O3 -D_NJ_EXAMPLE_PROGRAM -o nanojpeg nanojpeg.c
-// You may also add -std=c99 -Wall -Wextra -pedantic -Werror, if you want :)
-// The only thing you might need is -Wno-shift-negative-value, because this
-// code relies on the target machine using two's complement arithmetic, but
-// the C standard does not, even though *any* practically useful machine
-// nowadays uses two's complement.
-///////////////////////////////////////////////////////////////////////////////
-// HEADER SECTION                                                            //
-// copy and pase this into nanojpeg.h if you want                            //
-///////////////////////////////////////////////////////////////////////////////
-#ifndef _NANOJPEG_H
-#define _NANOJPEG_H
-// nj_result_t: Result codes for njDecode().
-typedef enum _nj_result {
-    NJ_OK = 0,        // no error, decoding successful
-    NJ_NO_JPEG,       // not a JPEG file
-    NJ_UNSUPPORTED,   // unsupported format
-    NJ_OUT_OF_MEM,    // out of memory
-    NJ_INTERNAL_ERR,  // internal error
-    NJ_SYNTAX_ERROR,  // syntax error
-    __NJ_FINISHED,    // used internally, will never be reported
-} nj_result_t;
-// njInit: Initialize NanoJPEG.
-// For safety reasons, this should be called at least one time before using
-// using any of the other NanoJPEG functions.
-void njInit(void);
-// njDecode: Decode a JPEG image.
-// Decodes a memory dump of a JPEG file into internal buffers.
-// Parameters:
-//   jpeg = The pointer to the memory dump.
-//   size = The size of the JPEG file.
-// Return value: The error code in case of failure, or NJ_OK (zero) on success.
-nj_result_t njDecode(const void* jpeg, const int size);
-// njGetWidth: Return the width (in pixels) of the most recently decoded
-// image. If njDecode() failed, the result of njGetWidth() is undefined.
-int njGetWidth(void);
-// njGetHeight: Return the height (in pixels) of the most recently decoded
-// image. If njDecode() failed, the result of njGetHeight() is undefined.
-int njGetHeight(void);
-// njIsColor: Return 1 if the most recently decoded image is a color image
-// (RGB) or 0 if it is a grayscale image. If njDecode() failed, the result
-// of njGetWidth() is undefined.
-int njIsColor(void);
-// njGetImage: Returns the decoded image data.
-// Returns a pointer to the most recently image. The memory layout it byte-
-// oriented, top-down, without any padding between lines. Pixels of color
-// images will be stored as three consecutive bytes for the red, green and
-// blue channels. This data format is thus compatible with the PGM or PPM
-// file formats and the OpenGL texture formats GL_LUMINANCE8 or GL_RGB8.
-// If njDecode() failed, the result of njGetImage() is undefined.
-unsigned char* njGetImage(void);
-// njGetImageSize: Returns the size (in bytes) of the image data returned
-// by njGetImage(). If njDecode() failed, the result of njGetImageSize() is
-// undefined.
-int njGetImageSize(void);
-// njDone: Uninitialize NanoJPEG.
-// Resets NanoJPEG's internal state and frees all memory that has been
-// allocated at run-time by NanoJPEG. It is still possible to decode another
-// image after a njDone() call.
-void njDone(void);
-#endif//_NANOJPEG_H
-///////////////////////////////////////////////////////////////////////////////
-// CONFIGURATION SECTION                                                     //
-// adjust the default settings for the NJ_ defines here                      //
-///////////////////////////////////////////////////////////////////////////////
-#ifndef NJ_USE_LIBC
-    #define NJ_USE_LIBC 1
-#endif
-#ifndef NJ_USE_WIN32
-  #ifdef _MSC_VER
-    #define NJ_USE_WIN32 (!NJ_USE_LIBC)
-  #else
-    #define NJ_USE_WIN32 0
-  #endif
-#endif
-#ifndef NJ_CHROMA_FILTER
-    #define NJ_CHROMA_FILTER 1
-#endif
-///////////////////////////////////////////////////////////////////////////////
-// EXAMPLE PROGRAM                                                           //
-// just define _NJ_EXAMPLE_PROGRAM to compile this (requires NJ_USE_LIBC)    //
-///////////////////////////////////////////////////////////////////////////////
-#ifdef  _NJ_EXAMPLE_PROGRAM
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-int main(int argc, char* argv[]) {
-    int size;
-    char *buf;
-    FILE *f;
-    if (argc < 2) {
-        printf("Usage: %s <input.jpg> [<output.ppm>]\n", argv[0]);
-        return 2;
-    }
-    f = fopen(argv[1], "rb");
-    if (!f) {
-        printf("Error opening the input file.\n");
-        return 1;
-    }
-    fseek(f, 0, SEEK_END);
-    size = (int) ftell(f);
-    buf = (char*) malloc(size);
-    fseek(f, 0, SEEK_SET);
-    size = (int) fread(buf, 1, size, f);
-    fclose(f);
-    njInit();
-    if (njDecode(buf, size)) {
-        free((void*)buf);
-        printf("Error decoding the input file.\n");
-        return 1;
-    }
-    free((void*)buf);
-    f = fopen((argc > 2) ? argv[2] : (njIsColor() ? "nanojpeg_out.ppm" : "nanojpeg_out.pgm"), "wb");
-    if (!f) {
-        printf("Error opening the output file.\n");
-        return 1;
-    }
-    fprintf(f, "P%d\n%d %d\n255\n", njIsColor() ? 6 : 5, njGetWidth(), njGetHeight());
-    fwrite(njGetImage(), 1, njGetImageSize(), f);
-    fclose(f);
-    njDone();
-    return 0;
-}
-#endif
-///////////////////////////////////////////////////////////////////////////////
-// IMPLEMENTATION SECTION                                                    //
-// you may stop reading here                                                 //
-///////////////////////////////////////////////////////////////////////////////
-#ifndef _NJ_INCLUDE_HEADER_ONLY
-#ifdef _MSC_VER
-    #define NJ_INLINE static __inline
-    #define NJ_FORCE_INLINE static __forceinline
-#else
-    #define NJ_INLINE static inline
-    #define NJ_FORCE_INLINE static inline
-#endif
-#if NJ_USE_LIBC
-    #include <stdlib.h>
-    #include <string.h>
-    #define njAllocMem malloc
-    #define njFreeMem  free
-    #define njFillMem  memset
-    #define njCopyMem  memcpy
-#elif NJ_USE_WIN32
-    #include <windows.h>
-    #define njAllocMem(size) ((void*) LocalAlloc(LMEM_FIXED, (SIZE_T)(size)))
-    #define njFreeMem(block) ((void) LocalFree((HLOCAL) block))
-    NJ_INLINE void njFillMem(void* block, unsigned char value, int count) { __asm {
-        mov edi, block
-        mov al, value
-        mov ecx, count
-        rep stosb
-    } }
-    NJ_INLINE void njCopyMem(void* dest, const void* src, int count) { __asm {
-        mov edi, dest
-        mov esi, src
-        mov ecx, count
-        rep movsb
-    } }
-#else
-    extern void* njAllocMem(int size);
-    extern void njFreeMem(void* block);
-    extern void njFillMem(void* block, unsigned char byte, int size);
-    extern void njCopyMem(void* dest, const void* src, int size);
-#endif
-typedef struct _nj_code {
-    unsigned char bits, code;
-} nj_vlc_code_t;
-typedef struct _nj_cmp {
-    int cid;
-    int ssx, ssy;
-    int width, height;
-    int stride;
-    int qtsel;
-    int actabsel, dctabsel;
-    int dcpred;
-    unsigned char *pixels;
-} nj_component_t;
-typedef struct _nj_ctx {
-    nj_result_t error;
-    const unsigned char *pos;
-    int size;
-    int length;
-    int width, height;
-    int mbwidth, mbheight;
-    int mbsizex, mbsizey;
-    int ncomp;
-    nj_component_t comp[3];
-    int qtused, qtavail;
-    unsigned char qtab[4][64];
-    nj_vlc_code_t vlctab[4][65536];
-    int buf, bufbits;
-    int block[64];
-    int rstinterval;
-    unsigned char *rgb;
-} nj_context_t;
-static nj_context_t nj;
-static const char njZZ[64] = { 0, 1, 8, 16, 9, 2, 3, 10, 17, 24, 32, 25, 18,
-, 4, 5, 12, 19, 26, 33, 40, 48, 41, 34, 27, 20, 13, 6, 7, 14, 21, 28, 35,
-, 49, 56, 57, 50, 43, 36, 29, 22, 15, 23, 30, 37, 44, 51, 58, 59, 52, 45,
-, 31, 39, 46, 53, 60, 61, 54, 47, 55, 62, 63 };
-NJ_FORCE_INLINE unsigned char njClip(const int x) {
-    return (x < 0) ? 0 : ((x > 0xFF) ? 0xFF : (unsigned char) x);
-}
-#define W1 2841
-#define W2 2676
-#define W3 2408
-#define W5 1609
-#define W6 1108
-#define W7 565
-NJ_INLINE void njRowIDCT(int* blk) {
-    int x0, x1, x2, x3, x4, x5, x6, x7, x8;
-    if (!((x1 = blk[4] << 11)
-        | (x2 = blk[6])
-        | (x3 = blk[2])
-        | (x4 = blk[1])
-        | (x5 = blk[7])
-        | (x6 = blk[5])
-        | (x7 = blk[3])))
-    {
-        blk[0] = blk[1] = blk[2] = blk[3] = blk[4] = blk[5] = blk[6] = blk[7] = blk[0] << 3;
-        return;
-    }
-    x0 = (blk[0] << 11) + 128;
-    x8 = W7 * (x4 + x5);
-    x4 = x8 + (W1 - W7) * x4;
-    x5 = x8 - (W1 + W7) * x5;
-    x8 = W3 * (x6 + x7);
-    x6 = x8 - (W3 - W5) * x6;
-    x7 = x8 - (W3 + W5) * x7;
-    x8 = x0 + x1;
-    x0 -= x1;
-    x1 = W6 * (x3 + x2);
-    x2 = x1 - (W2 + W6) * x2;
-    x3 = x1 + (W2 - W6) * x3;
-    x1 = x4 + x6;
-    x4 -= x6;
-    x6 = x5 + x7;
-    x5 -= x7;
-    x7 = x8 + x3;
-    x8 -= x3;
-    x3 = x0 + x2;
-    x0 -= x2;
-    x2 = (181 * (x4 + x5) + 128) >> 8;
-    x4 = (181 * (x4 - x5) + 128) >> 8;
-    blk[0] = (x7 + x1) >> 8;
-    blk[1] = (x3 + x2) >> 8;
-    blk[2] = (x0 + x4) >> 8;
-    blk[3] = (x8 + x6) >> 8;
-    blk[4] = (x8 - x6) >> 8;
-    blk[5] = (x0 - x4) >> 8;
-    blk[6] = (x3 - x2) >> 8;
-    blk[7] = (x7 - x1) >> 8;
-}
-NJ_INLINE void njColIDCT(const int* blk, unsigned char *out, int stride) {
-    int x0, x1, x2, x3, x4, x5, x6, x7, x8;
-    if (!((x1 = blk[8*4] << 8)
-        | (x2 = blk[8*6])
-        | (x3 = blk[8*2])
-        | (x4 = blk[8*1])
-        | (x5 = blk[8*7])
-        | (x6 = blk[8*5])
-        | (x7 = blk[8*3])))
-    {
-        x1 = njClip(((blk[0] + 32) >> 6) + 128);
-        for (x0 = 8;  x0;  --x0) {
-            *out = (unsigned char) x1;
-            out += stride;
-        }
-        return;
-    }
-    x0 = (blk[0] << 8) + 8192;
-    x8 = W7 * (x4 + x5) + 4;
-    x4 = (x8 + (W1 - W7) * x4) >> 3;
-    x5 = (x8 - (W1 + W7) * x5) >> 3;
-    x8 = W3 * (x6 + x7) + 4;
-    x6 = (x8 - (W3 - W5) * x6) >> 3;
-    x7 = (x8 - (W3 + W5) * x7) >> 3;
-    x8 = x0 + x1;
-    x0 -= x1;
-    x1 = W6 * (x3 + x2) + 4;
-    x2 = (x1 - (W2 + W6) * x2) >> 3;
-    x3 = (x1 + (W2 - W6) * x3) >> 3;
-    x1 = x4 + x6;
-    x4 -= x6;
-    x6 = x5 + x7;
-    x5 -= x7;
-    x7 = x8 + x3;
-    x8 -= x3;
-    x3 = x0 + x2;
-    x0 -= x2;
-    x2 = (181 * (x4 + x5) + 128) >> 8;
-    x4 = (181 * (x4 - x5) + 128) >> 8;
-    *out = njClip(((x7 + x1) >> 14) + 128);  out += stride;
-    *out = njClip(((x3 + x2) >> 14) + 128);  out += stride;
-    *out = njClip(((x0 + x4) >> 14) + 128);  out += stride;
-    *out = njClip(((x8 + x6) >> 14) + 128);  out += stride;
-    *out = njClip(((x8 - x6) >> 14) + 128);  out += stride;
-    *out = njClip(((x0 - x4) >> 14) + 128);  out += stride;
-    *out = njClip(((x3 - x2) >> 14) + 128);  out += stride;
-    *out = njClip(((x7 - x1) >> 14) + 128);
-}
-#define njThrow(e) do { nj.error = e; return; } while (0)
-#define njCheckError() do { if (nj.error) return; } while (0)
-static int njShowBits(int bits) {
-    unsigned char newbyte;
-    if (!bits) return 0;
-    while (nj.bufbits < bits) {
-        if (nj.size <= 0) {
-            nj.buf = (nj.buf << 8) | 0xFF;
-            nj.bufbits += 8;
-            continue;
-        }
-        newbyte = *nj.pos++;
-        nj.size--;
-        nj.bufbits += 8;
-        nj.buf = (nj.buf << 8) | newbyte;
-        if (newbyte == 0xFF) {
-            if (nj.size) {
-                unsigned char marker = *nj.pos++;
-                nj.size--;
-                switch (marker) {
-                    case 0x00:
-                    case 0xFF:
-                        break;
-                    case 0xD9: nj.size = 0; break;
-                    default:
-                        if ((marker & 0xF8) != 0xD0)
-                            nj.error = NJ_SYNTAX_ERROR;
-                        else {
-                            nj.buf = (nj.buf << 8) | marker;
-                            nj.bufbits += 8;
-                        }
-                }
-            } else
-                nj.error = NJ_SYNTAX_ERROR;
-        }
-    }
-    return (nj.buf >> (nj.bufbits - bits)) & ((1 << bits) - 1);
-}
-NJ_INLINE void njSkipBits(int bits) {
-    if (nj.bufbits < bits)
-        (void) njShowBits(bits);
-    nj.bufbits -= bits;
-}
-NJ_INLINE int njGetBits(int bits) {
-    int res = njShowBits(bits);
-    njSkipBits(bits);
-    return res;
-}
-NJ_INLINE void njByteAlign(void) {
-    nj.bufbits &= 0xF8;
-}
-static void njSkip(int count) {
-    nj.pos += count;
-    nj.size -= count;
-    nj.length -= count;
-    if (nj.size < 0) nj.error = NJ_SYNTAX_ERROR;
-}
-NJ_INLINE unsigned short njDecode16(const unsigned char *pos) {
-    return (pos[0] << 8) | pos[1];
-}
-static void njDecodeLength(void) {
-    if (nj.size < 2) njThrow(NJ_SYNTAX_ERROR);
-    nj.length = njDecode16(nj.pos);
-    if (nj.length > nj.size) njThrow(NJ_SYNTAX_ERROR);
-    njSkip(2);
-}
-NJ_INLINE void njSkipMarker(void) {
-    njDecodeLength();
-    njSkip(nj.length);
-}
-NJ_INLINE void njDecodeSOF(void) {
-    int i, ssxmax = 0, ssymax = 0;
-    nj_component_t* c;
-    njDecodeLength();
-    njCheckError();
-    if (nj.length < 9) njThrow(NJ_SYNTAX_ERROR);
-    if (nj.pos[0] != 8) njThrow(NJ_UNSUPPORTED);
-    nj.height = njDecode16(nj.pos+1);
-    nj.width = njDecode16(nj.pos+3);
-    if (!nj.width || !nj.height) njThrow(NJ_SYNTAX_ERROR);
-    nj.ncomp = nj.pos[5];
-    njSkip(6);
-    switch (nj.ncomp) {
-        case 1:
-        case 3:
-            break;
-        default:
-            njThrow(NJ_UNSUPPORTED);
-    }
-    if (nj.length < (nj.ncomp * 3)) njThrow(NJ_SYNTAX_ERROR);
-    for (i = 0, c = nj.comp;  i < nj.ncomp;  ++i, ++c) {
-        c->cid = nj.pos[0];
-        if (!(c->ssx = nj.pos[1] >> 4)) njThrow(NJ_SYNTAX_ERROR);
-        if (c->ssx & (c->ssx - 1)) njThrow(NJ_UNSUPPORTED);  // non-power of two
-        if (!(c->ssy = nj.pos[1] & 15)) njThrow(NJ_SYNTAX_ERROR);
-        if (c->ssy & (c->ssy - 1)) njThrow(NJ_UNSUPPORTED);  // non-power of two
-        if ((c->qtsel = nj.pos[2]) & 0xFC) njThrow(NJ_SYNTAX_ERROR);
-        njSkip(3);
-        nj.qtused |= 1 << c->qtsel;
-        if (c->ssx > ssxmax) ssxmax = c->ssx;
-        if (c->ssy > ssymax) ssymax = c->ssy;
-    }
-    if (nj.ncomp == 1) {
-        c = nj.comp;
-        c->ssx = c->ssy = ssxmax = ssymax = 1;
-    }
-    nj.mbsizex = ssxmax << 3;
-    nj.mbsizey = ssymax << 3;
-    nj.mbwidth = (nj.width + nj.mbsizex - 1) / nj.mbsizex;
-    nj.mbheight = (nj.height + nj.mbsizey - 1) / nj.mbsizey;
-    for (i = 0, c = nj.comp;  i < nj.ncomp;  ++i, ++c) {
-        c->width = (nj.width * c->ssx + ssxmax - 1) / ssxmax;
-        c->height = (nj.height * c->ssy + ssymax - 1) / ssymax;
-        c->stride = nj.mbwidth * c->ssx << 3;
-        if (((c->width < 3) && (c->ssx != ssxmax)) || ((c->height < 3) && (c->ssy != ssymax))) njThrow(NJ_UNSUPPORTED);
-        if (!(c->pixels = (unsigned char*) njAllocMem(c->stride * nj.mbheight * c->ssy << 3))) njThrow(NJ_OUT_OF_MEM);
-    }
-    if (nj.ncomp == 3) {
-        nj.rgb = (unsigned char*) njAllocMem(nj.width * nj.height * nj.ncomp);
-        if (!nj.rgb) njThrow(NJ_OUT_OF_MEM);
-    }
-    njSkip(nj.length);
-}
-NJ_INLINE void njDecodeDHT(void) {
-    int codelen, currcnt, remain, spread, i, j;
-    nj_vlc_code_t *vlc;
-    static unsigned char counts[16];
-    njDecodeLength();
-    njCheckError();
-    while (nj.length >= 17) {
-        i = nj.pos[0];
-        if (i & 0xEC) njThrow(NJ_SYNTAX_ERROR);
-        if (i & 0x02) njThrow(NJ_UNSUPPORTED);
-        i = (i | (i >> 3)) & 3;  // combined DC/AC + tableid value
-        for (codelen = 1;  codelen <= 16;  ++codelen)
-            counts[codelen - 1] = nj.pos[codelen];
-        njSkip(17);
-        vlc = &nj.vlctab[i][0];
-        remain = spread = 65536;
-        for (codelen = 1;  codelen <= 16;  ++codelen) {
-            spread >>= 1;
-            currcnt = counts[codelen - 1];
-            if (!currcnt) continue;
-            if (nj.length < currcnt) njThrow(NJ_SYNTAX_ERROR);
-            remain -= currcnt << (16 - codelen);
-            if (remain < 0) njThrow(NJ_SYNTAX_ERROR);
-            for (i = 0;  i < currcnt;  ++i) {
-                register unsigned char code = nj.pos[i];
-                for (j = spread;  j;  --j) {
-                    vlc->bits = (unsigned char) codelen;
-                    vlc->code = code;
-                    ++vlc;
-                }
-            }
-            njSkip(currcnt);
-        }
-        while (remain--) {
-            vlc->bits = 0;
-            ++vlc;
-        }
-    }
-    if (nj.length) njThrow(NJ_SYNTAX_ERROR);
-}
-NJ_INLINE void njDecodeDQT(void) {
-    int i;
-    unsigned char *t;
-    njDecodeLength();
-    njCheckError();
-    while (nj.length >= 65) {
-        i = nj.pos[0];
-        if (i & 0xFC) njThrow(NJ_SYNTAX_ERROR);
-        nj.qtavail |= 1 << i;
-        t = &nj.qtab[i][0];
-        for (i = 0;  i < 64;  ++i)
-            t[i] = nj.pos[i + 1];
-        njSkip(65);
-    }
-    if (nj.length) njThrow(NJ_SYNTAX_ERROR);
-}
-NJ_INLINE void njDecodeDRI(void) {
-    njDecodeLength();
-    njCheckError();
-    if (nj.length < 2) njThrow(NJ_SYNTAX_ERROR);
-    nj.rstinterval = njDecode16(nj.pos);
-    njSkip(nj.length);
-}
-static int njGetVLC(nj_vlc_code_t* vlc, unsigned char* code) {
-    int value = njShowBits(16);
-    int bits = vlc[value].bits;
-    if (!bits) { nj.error = NJ_SYNTAX_ERROR; return 0; }
-    njSkipBits(bits);
-    value = vlc[value].code;
-    if (code) *code = (unsigned char) value;
-    bits = value & 15;
-    if (!bits) return 0;
-    value = njGetBits(bits);
-    if (value < (1 << (bits - 1)))
-        value += ((-1) << bits) + 1;
-    return value;
-}
-NJ_INLINE void njDecodeBlock(nj_component_t* c, unsigned char* out) {
-    unsigned char code = 0;
-    int value, coef = 0;
-    njFillMem(nj.block, 0, sizeof(nj.block));
-    c->dcpred += njGetVLC(&nj.vlctab[c->dctabsel][0], NULL);
-    nj.block[0] = (c->dcpred) * nj.qtab[c->qtsel][0];
-    do {
-        value = njGetVLC(&nj.vlctab[c->actabsel][0], &code);
-        if (!code) break;  // EOB
-        if (!(code & 0x0F) && (code != 0xF0)) njThrow(NJ_SYNTAX_ERROR);
-        coef += (code >> 4) + 1;
-        if (coef > 63) njThrow(NJ_SYNTAX_ERROR);
-        nj.block[(int) njZZ[coef]] = value * nj.qtab[c->qtsel][coef];
-    } while (coef < 63);
-    for (coef = 0;  coef < 64;  coef += 8)
-        njRowIDCT(&nj.block[coef]);
-    for (coef = 0;  coef < 8;  ++coef)
-        njColIDCT(&nj.block[coef], &out[coef], c->stride);
-}
-NJ_INLINE void njDecodeScan(void) {
-    int i, mbx, mby, sbx, sby;
-    int rstcount = nj.rstinterval, nextrst = 0;
-    nj_component_t* c;
-    njDecodeLength();
-    njCheckError();
-    if (nj.length < (4 + 2 * nj.ncomp)) njThrow(NJ_SYNTAX_ERROR);
-    if (nj.pos[0] != nj.ncomp) njThrow(NJ_UNSUPPORTED);
-    njSkip(1);
-    for (i = 0, c = nj.comp;  i < nj.ncomp;  ++i, ++c) {
-        if (nj.pos[0] != c->cid) njThrow(NJ_SYNTAX_ERROR);
-        if (nj.pos[1] & 0xEE) njThrow(NJ_SYNTAX_ERROR);
-        c->dctabsel = nj.pos[1] >> 4;
-        c->actabsel = (nj.pos[1] & 1) | 2;
-        njSkip(2);
-    }
-    if (nj.pos[0] || (nj.pos[1] != 63) || nj.pos[2]) njThrow(NJ_UNSUPPORTED);
-    njSkip(nj.length);
-    for (mbx = mby = 0;;) {
-        for (i = 0, c = nj.comp;  i < nj.ncomp;  ++i, ++c)
-            for (sby = 0;  sby < c->ssy;  ++sby)
-                for (sbx = 0;  sbx < c->ssx;  ++sbx) {
-                    njDecodeBlock(c, &c->pixels[((mby * c->ssy + sby) * c->stride + mbx * c->ssx + sbx) << 3]);
-                    njCheckError();
-                }
-        if (++mbx >= nj.mbwidth) {
-            mbx = 0;
-            if (++mby >= nj.mbheight) break;
-        }
-        if (nj.rstinterval && !(--rstcount)) {
-            njByteAlign();
-            i = njGetBits(16);
-            if (((i & 0xFFF8) != 0xFFD0) || ((i & 7) != nextrst)) njThrow(NJ_SYNTAX_ERROR);
-            nextrst = (nextrst + 1) & 7;
-            rstcount = nj.rstinterval;
-            for (i = 0;  i < 3;  ++i)
-                nj.comp[i].dcpred = 0;
-        }
-    }
-    nj.error = __NJ_FINISHED;
-}
-#if NJ_CHROMA_FILTER
-#define CF4A (-9)
-#define CF4B (111)
-#define CF4C (29)
-#define CF4D (-3)
-#define CF3A (28)
-#define CF3B (109)
-#define CF3C (-9)
-#define CF3X (104)
-#define CF3Y (27)
-#define CF3Z (-3)
-#define CF2A (139)
-#define CF2B (-11)
-#define CF(x) njClip(((x) + 64) >> 7)
-NJ_INLINE void njUpsampleH(nj_component_t* c) {
-    const int xmax = c->width - 3;
-    unsigned char *out, *lin, *lout;
-    int x, y;
-    out = (unsigned char*) njAllocMem((c->width * c->height) << 1);
-    if (!out) njThrow(NJ_OUT_OF_MEM);
-    lin = c->pixels;
-    lout = out;
-    for (y = c->height;  y;  --y) {
-        lout[0] = CF(CF2A * lin[0] + CF2B * lin[1]);
-        lout[1] = CF(CF3X * lin[0] + CF3Y * lin[1] + CF3Z * lin[2]);
-        lout[2] = CF(CF3A * lin[0] + CF3B * lin[1] + CF3C * lin[2]);
-        for (x = 0;  x < xmax;  ++x) {
-            lout[(x << 1) + 3] = CF(CF4A * lin[x] + CF4B * lin[x + 1] + CF4C * lin[x + 2] + CF4D * lin[x + 3]);
-            lout[(x << 1) + 4] = CF(CF4D * lin[x] + CF4C * lin[x + 1] + CF4B * lin[x + 2] + CF4A * lin[x + 3]);
-        }
-        lin += c->stride;
-        lout += c->width << 1;
-        lout[-3] = CF(CF3A * lin[-1] + CF3B * lin[-2] + CF3C * lin[-3]);
-        lout[-2] = CF(CF3X * lin[-1] + CF3Y * lin[-2] + CF3Z * lin[-3]);
-        lout[-1] = CF(CF2A * lin[-1] + CF2B * lin[-2]);
-    }
-    c->width <<= 1;
-    c->stride = c->width;
-    njFreeMem((void*)c->pixels);
-    c->pixels = out;
-}
-NJ_INLINE void njUpsampleV(nj_component_t* c) {
-    const int w = c->width, s1 = c->stride, s2 = s1 + s1;
-    unsigned char *out, *cin, *cout;
-    int x, y;
-    out = (unsigned char*) njAllocMem((c->width * c->height) << 1);
-    if (!out) njThrow(NJ_OUT_OF_MEM);
-    for (x = 0;  x < w;  ++x) {
-        cin = &c->pixels[x];
-        cout = &out[x];
-        *cout = CF(CF2A * cin[0] + CF2B * cin[s1]);  cout += w;
-        *cout = CF(CF3X * cin[0] + CF3Y * cin[s1] + CF3Z * cin[s2]);  cout += w;
-        *cout = CF(CF3A * cin[0] + CF3B * cin[s1] + CF3C * cin[s2]);  cout += w;
-        cin += s1;
-        for (y = c->height - 3;  y;  --y) {
-            *cout = CF(CF4A * cin[-s1] + CF4B * cin[0] + CF4C * cin[s1] + CF4D * cin[s2]);  cout += w;
-            *cout = CF(CF4D * cin[-s1] + CF4C * cin[0] + CF4B * cin[s1] + CF4A * cin[s2]);  cout += w;
-            cin += s1;
-        }
-        cin += s1;
-        *cout = CF(CF3A * cin[0] + CF3B * cin[-s1] + CF3C * cin[-s2]);  cout += w;
-        *cout = CF(CF3X * cin[0] + CF3Y * cin[-s1] + CF3Z * cin[-s2]);  cout += w;
-        *cout = CF(CF2A * cin[0] + CF2B * cin[-s1]);
-    }
-    c->height <<= 1;
-    c->stride = c->width;
-    njFreeMem((void*) c->pixels);
-    c->pixels = out;
-}
-#else
-NJ_INLINE void njUpsample(nj_component_t* c) {
-    int x, y, xshift = 0, yshift = 0;
-    unsigned char *out, *lin, *lout;
-    while (c->width < nj.width) { c->width <<= 1; ++xshift; }
-    while (c->height < nj.height) { c->height <<= 1; ++yshift; }
-    out = (unsigned char*) njAllocMem(c->width * c->height);
-    if (!out) njThrow(NJ_OUT_OF_MEM);
-    lin = c->pixels;
-    lout = out;
-    for (y = 0;  y < c->height;  ++y) {
-        lin = &c->pixels[(y >> yshift) * c->stride];
-        for (x = 0;  x < c->width;  ++x)
-            lout[x] = lin[x >> xshift];
-        lout += c->width;
-    }
-    c->stride = c->width;
-    njFreeMem((void*) c->pixels);
-    c->pixels = out;
-}
-#endif
-NJ_INLINE void njConvert(void) {
-    int i;
-    nj_component_t* c;
-    for (i = 0, c = nj.comp;  i < nj.ncomp;  ++i, ++c) {
-        #if NJ_CHROMA_FILTER
-            while ((c->width < nj.width) || (c->height < nj.height)) {
-                if (c->width < nj.width) njUpsampleH(c);
-                njCheckError();
-                if (c->height < nj.height) njUpsampleV(c);
-                njCheckError();
-            }
-        #else
-            if ((c->width < nj.width) || (c->height < nj.height))
-                njUpsample(c);
-        #endif
-        if ((c->width < nj.width) || (c->height < nj.height)) njThrow(NJ_INTERNAL_ERR);
-    }
-    if (nj.ncomp == 3) {
-        // convert to RGB
-        int x, yy;
-        unsigned char *prgb = nj.rgb;
-        const unsigned char *py  = nj.comp[0].pixels;
-        const unsigned char *pcb = nj.comp[1].pixels;
-        const unsigned char *pcr = nj.comp[2].pixels;
-        for (yy = nj.height;  yy;  --yy) {
-            for (x = 0;  x < nj.width;  ++x) {
-                register int y = py[x] << 8;
-                register int cb = pcb[x] - 128;
-                register int cr = pcr[x] - 128;
-                *prgb++ = njClip((y            + 359 * cr + 128) >> 8);
-                *prgb++ = njClip((y -  88 * cb - 183 * cr + 128) >> 8);
-                *prgb++ = njClip((y + 454 * cb            + 128) >> 8);
-            }
-            py += nj.comp[0].stride;
-            pcb += nj.comp[1].stride;
-            pcr += nj.comp[2].stride;
-        }
-    } else if (nj.comp[0].width != nj.comp[0].stride) {
-        // grayscale -> only remove stride
-        unsigned char *pin = &nj.comp[0].pixels[nj.comp[0].stride];
-        unsigned char *pout = &nj.comp[0].pixels[nj.comp[0].width];
-        int y;
-        for (y = nj.comp[0].height - 1;  y;  --y) {
-            njCopyMem(pout, pin, nj.comp[0].width);
-            pin += nj.comp[0].stride;
-            pout += nj.comp[0].width;
-        }
-        nj.comp[0].stride = nj.comp[0].width;
-    }
-}
-void njInit(void) {
-    njFillMem(&nj, 0, sizeof(nj_context_t));
-}
-void njDone(void) {
-    int i;
-    for (i = 0;  i < 3;  ++i)
-        if (nj.comp[i].pixels) njFreeMem((void*) nj.comp[i].pixels);
-    if (nj.rgb) njFreeMem((void*) nj.rgb);
-    njInit();
-}
-nj_result_t njDecode(const void* jpeg, const int size) {
-    njDone();
-    nj.pos = (const unsigned char*) jpeg;
-    nj.size = size & 0x7FFFFFFF;
-    if (nj.size < 2) return NJ_NO_JPEG;
-    if ((nj.pos[0] ^ 0xFF) | (nj.pos[1] ^ 0xD8)) return NJ_NO_JPEG;
-    njSkip(2);
-    while (!nj.error) {
-        if ((nj.size < 2) || (nj.pos[0] != 0xFF)) return NJ_SYNTAX_ERROR;
-        njSkip(2);
-        switch (nj.pos[-1]) {
-            case 0xC0: njDecodeSOF();  break;
-            case 0xC4: njDecodeDHT();  break;
-            case 0xDB: njDecodeDQT();  break;
-            case 0xDD: njDecodeDRI();  break;
-            case 0xDA: njDecodeScan(); break;
-            case 0xFE: njSkipMarker(); break;
-            default:
-                if ((nj.pos[-1] & 0xF0) == 0xE0)
-                    njSkipMarker();
-                else
-                    return NJ_UNSUPPORTED;
-        }
-    }
-    if (nj.error != __NJ_FINISHED) return nj.error;
-    nj.error = NJ_OK;
-    njConvert();
-    return nj.error;
-}
-int njGetWidth(void)            { return nj.width; }
-int njGetHeight(void)           { return nj.height; }
-int njIsColor(void)             { return (nj.ncomp != 1); }
-unsigned char* njGetImage(void) { return (nj.ncomp == 1) ? nj.comp[0].pixels : nj.rgb; }
-int njGetImageSize(void)        { return nj.width * nj.height * nj.ncomp; }
-#endif // _NJ_INCLUDE_HEADER_ONLY
-</code>
-===== References =====
-http://svn.emphy.de/nanojpeg/trunk/nanojpeg/nanojpeg.c