Kyle Post / BaseJpegDecode

Any changes are to allow conversion to BMP

Dependents:   Color_Targeting_Catapult

Fork of BaseJpegDecode by Norimasa Okamoto

inverseDCT.cpp@2:5b1dd4e34857, 2012-10-30 (annotated)

Committer:
va009039
Date:
Tue Oct 30 13:22:08 2012 +0000
Revision:
2:5b1dd4e34857
Child:
3:a7547692071d
add inverseDCT

Who changed what in which revision?

UserRevisionLine numberNew contents of line
va009039 2:5b1dd4e34857 1 #include "mbed.h"
va009039 2:5b1dd4e34857 2 #include <math.h>
va009039 2:5b1dd4e34857 3 #include "inverseDCT.h"
va009039 2:5b1dd4e34857 4
va009039 2:5b1dd4e34857 5 #define PI 3.14159265
va009039 2:5b1dd4e34857 6
va009039 2:5b1dd4e34857 7 const int zigzag[64] =
va009039 2:5b1dd4e34857 8 {0,
va009039 2:5b1dd4e34857 9 1, 8,
va009039 2:5b1dd4e34857 10 16, 9, 2,
va009039 2:5b1dd4e34857 11 3,10,17,24,
va009039 2:5b1dd4e34857 12 32,25,18,11, 4,
va009039 2:5b1dd4e34857 13 5,12,19,26,33,40,
va009039 2:5b1dd4e34857 14 48,41,34,27,20,13,6,
va009039 2:5b1dd4e34857 15 7,14,21,28,35,42,49,56,
va009039 2:5b1dd4e34857 16 57,50,43,36,29,22,15,
va009039 2:5b1dd4e34857 17 23,30,37,44,51,58,
va009039 2:5b1dd4e34857 18 59,52,45,38,31,
va009039 2:5b1dd4e34857 19 39,46,53,60,
va009039 2:5b1dd4e34857 20 61,54,47,
va009039 2:5b1dd4e34857 21 55,62,
va009039 2:5b1dd4e34857 22 63};
va009039 2:5b1dd4e34857 23
va009039 2:5b1dd4e34857 24 int adjust(int value) {
va009039 2:5b1dd4e34857 25 value += 128;
va009039 2:5b1dd4e34857 26 if (value < 0) {
va009039 2:5b1dd4e34857 27 return 0;
va009039 2:5b1dd4e34857 28 } else if (value > 255) {
va009039 2:5b1dd4e34857 29 return 255;
va009039 2:5b1dd4e34857 30 }
va009039 2:5b1dd4e34857 31 return value;
va009039 2:5b1dd4e34857 32 }
va009039 2:5b1dd4e34857 33
va009039 2:5b1dd4e34857 34 #if DCT_USE_INT
va009039 2:5b1dd4e34857 35 inverseDCT::inverseDCT()
va009039 2:5b1dd4e34857 36 {
va009039 2:5b1dd4e34857 37 for(int x = 0; x < 8; x++) {
va009039 2:5b1dd4e34857 38 for(int u = 0; u < 8; u++) {
va009039 2:5b1dd4e34857 39 float value = cos((x*2+1)*u*PI/16);
va009039 2:5b1dd4e34857 40 m_cosxu[x*8+u] = value * 32;
va009039 2:5b1dd4e34857 41 }
va009039 2:5b1dd4e34857 42 }
va009039 2:5b1dd4e34857 43
va009039 2:5b1dd4e34857 44 for(int v = 0; v < 8; v++) {
va009039 2:5b1dd4e34857 45 for(int u = 0; u < 8; u++) {
va009039 2:5b1dd4e34857 46 float value = 1.0 / 4.0;
va009039 2:5b1dd4e34857 47 if (v == 0 && u == 0) {
va009039 2:5b1dd4e34857 48 value /= 2.0;
va009039 2:5b1dd4e34857 49 } else if (v == 0 || u == 0) {
va009039 2:5b1dd4e34857 50 value /= sqrt(2.0);
va009039 2:5b1dd4e34857 51 }
va009039 2:5b1dd4e34857 52 m_cucv[v*8+u] = value * 32;
va009039 2:5b1dd4e34857 53 }
va009039 2:5b1dd4e34857 54 }
va009039 2:5b1dd4e34857 55 }
va009039 2:5b1dd4e34857 56
va009039 2:5b1dd4e34857 57 void inverseDCT::inputBLOCK(int mcu, int block, int scan, int value)
va009039 2:5b1dd4e34857 58 {
va009039 2:5b1dd4e34857 59 if (scan == 0) {
va009039 2:5b1dd4e34857 60 for(int i = 0; i < 64; i++) {
va009039 2:5b1dd4e34857 61 m_sum[i] = 0;
va009039 2:5b1dd4e34857 62 }
va009039 2:5b1dd4e34857 63 }
va009039 2:5b1dd4e34857 64
va009039 2:5b1dd4e34857 65 if (value != 0) {
va009039 2:5b1dd4e34857 66 int uv = zigzag[scan];
va009039 2:5b1dd4e34857 67 int u = uv % 8;
va009039 2:5b1dd4e34857 68 int v = uv / 8;
va009039 2:5b1dd4e34857 69 for(int y = 0; y < 8; y++) {
va009039 2:5b1dd4e34857 70 for(int x = 0; x < 8; x++) {
va009039 2:5b1dd4e34857 71 int t = m_cucv[uv] * value * m_cosxu[x*8+u] * m_cosxu[y*8+v] / 32 / 32;
va009039 2:5b1dd4e34857 72 m_sum[y*8+x] += t;
va009039 2:5b1dd4e34857 73 }
va009039 2:5b1dd4e34857 74 }
va009039 2:5b1dd4e34857 75 }
va009039 2:5b1dd4e34857 76
va009039 2:5b1dd4e34857 77 if (scan == 63) {
va009039 2:5b1dd4e34857 78 uint8_t result[64];
va009039 2:5b1dd4e34857 79 for(int i = 0; i < 64; i++) {
va009039 2:5b1dd4e34857 80 int value = m_sum[i] / 32;
va009039 2:5b1dd4e34857 81 result[i] = adjust(value);
va009039 2:5b1dd4e34857 82 }
va009039 2:5b1dd4e34857 83 outputBLOCK(mcu, block, result);
va009039 2:5b1dd4e34857 84 }
va009039 2:5b1dd4e34857 85 }
va009039 2:5b1dd4e34857 86
va009039 2:5b1dd4e34857 87 #else
va009039 2:5b1dd4e34857 88
va009039 2:5b1dd4e34857 89 inverseDCT::inverseDCT()
va009039 2:5b1dd4e34857 90 {
va009039 2:5b1dd4e34857 91 }
va009039 2:5b1dd4e34857 92
va009039 2:5b1dd4e34857 93 void inverseDCT::input(int mcu, int block, int scan, int value) {
va009039 2:5b1dd4e34857 94 if (scan == 0) {
va009039 2:5b1dd4e34857 95 for(int i = 0; i < 64; i++) {
va009039 2:5b1dd4e34857 96 m_s[i] = 0;
va009039 2:5b1dd4e34857 97 }
va009039 2:5b1dd4e34857 98 }
va009039 2:5b1dd4e34857 99 m_s[zigzag[scan]] = value;
va009039 2:5b1dd4e34857 100 if (scan == 63) {
va009039 2:5b1dd4e34857 101 calc(mcu, block, m_s);
va009039 2:5b1dd4e34857 102 }
va009039 2:5b1dd4e34857 103 }
va009039 2:5b1dd4e34857 104
va009039 2:5b1dd4e34857 105 void inverseDCT::calc(int mcu, int block, int s[]) {
va009039 2:5b1dd4e34857 106 for(int y = 0; y < 8; y++) {
va009039 2:5b1dd4e34857 107 for(int x = 0; x < 8; x++) {
va009039 2:5b1dd4e34857 108 float sum = 0.0;
va009039 2:5b1dd4e34857 109 for(int v = 0; v < 8; v++) {
va009039 2:5b1dd4e34857 110 float cv = 1.0;
va009039 2:5b1dd4e34857 111 if (v == 0) {
va009039 2:5b1dd4e34857 112 cv /= sqrt(2.0);
va009039 2:5b1dd4e34857 113 }
va009039 2:5b1dd4e34857 114 for(int u = 0; u < 8; u++) {
va009039 2:5b1dd4e34857 115 float cu = 1.0;
va009039 2:5b1dd4e34857 116 if (u == 0) {
va009039 2:5b1dd4e34857 117 cu /= sqrt(2.0);
va009039 2:5b1dd4e34857 118 }
va009039 2:5b1dd4e34857 119 int vu = v * 8 + u;
va009039 2:5b1dd4e34857 120 float cosxu = cos((x*2+1) * u * PI / 16);
va009039 2:5b1dd4e34857 121 float cosyv = cos((y*2+1) * v * PI / 16);
va009039 2:5b1dd4e34857 122 sum += cu * cv * s[vu] * cosxu * cosyv;
va009039 2:5b1dd4e34857 123 }
va009039 2:5b1dd4e34857 124 }
va009039 2:5b1dd4e34857 125 sum /= 4;
va009039 2:5b1dd4e34857 126 m_result[y*8+x] = adjust(sum);
va009039 2:5b1dd4e34857 127 }
va009039 2:5b1dd4e34857 128 }
va009039 2:5b1dd4e34857 129 }
va009039 2:5b1dd4e34857 130 #endif