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Add tests and IDCT... now we need to fix the tests so they pass

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This commit is contained in:
Pavel Krajcevski 2015-02-19 00:53:20 -08:00
parent 4afacf384d
commit 1f2358be79
3 changed files with 101 additions and 9 deletions
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1
Base/include/FasTC/Image.h
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@ -132,6 +132,7 @@ namespace FasTC {
Image<IPixel> *channelThree);
extern void DiscreteCosineXForm(Image<IPixel> *img, int blockSize);
extern void InvDiscreteCosineXForm(Image<IPixel> *img, int blockSize);
} // namespace FasTC
#endif // __TEXCOMP_IMAGE_H__

72
Base/src/Image.cpp
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@ -48,6 +48,8 @@
#include <cstdio>
#include <cstring>
#include <cassert>
#define _USE_MATH_DEFINES
#include <cmath>
#include "FasTC/Color.h"
@ -616,6 +618,8 @@ void SplitChannels<Pixel>(const Image<Pixel> &in,
//
////////////////////////////////////////////////////////////////////////////////
typedef void (*DCTBlockFn)(Image<IPixel> *);
static void DCT(Image<IPixel> *img) {
Image<IPixel> new_img = *img;
@ -625,29 +629,74 @@ static void DCT(Image<IPixel> *img) {
for (unsigned int v = 0; v < img->GetHeight(); ++v) {
for (unsigned int u = 0; u < img->GetWidth(); ++u) {
new_img(u, v) = 0.0f;
float fu = static_cast<float>(u);
float fv = static_cast<float>(v);
for (unsigned int y = 0; y < img->GetHeight(); ++y) {
for (unsigned int x = 0; x < img->GetWidth(); ++x) {
float fx = static_cast<float>(x);
float fy = static_cast<float>(y);
new_img(u, v) += (*img)(x, y)
* cos((2*fx + 1) / (2 * N))
* cos((2*fy + 1) / (2 * M));
* cos(((2*fx + 1) * fu * M_PI) / (2 * N))
* cos(((2*fy + 1) * fv * M_PI) / (2 * M));
}
}
if (u == 0 && v == 0) {
new_img(u, v) *= 0.5;
new_img(u, v) /= N;
} else if (u == 0 || v == 0) {
new_img(u, v) /= sqrt(2);
new_img(u, v) *= sqrt(2) / N;
} else {
new_img(u, v) *= 2 / N;
}
new_img(u, v) *= 0.25;
}
}
*img = new_img;
}
extern void DiscreteCosineXForm(Image<IPixel> *img, int blockSize) {
static void IDCT(Image<IPixel> *img) {
Image<IPixel> new_img = *img;
float N = static_cast<float>(img->GetWidth());
float M = static_cast<float>(img->GetHeight());
assert (N == M);
for (unsigned int y = 0; y < img->GetHeight(); ++y) {
for (unsigned int x = 0; x < img->GetWidth(); ++x) {
new_img(x, y) = 0.0f;
float fx = static_cast<float>(x);
float fy = static_cast<float>(y);
for (unsigned int v = 0; v < img->GetHeight(); ++v) {
for (unsigned int u = 0; u < img->GetWidth(); ++u) {
float fu = static_cast<float>(u);
float fv = static_cast<float>(v);
new_img(x, y) += (*img)(u, v)
* cos(((2*fx + 1) * fu * M_PI) / (2 * N))
* cos(((2*fy + 1) * fv * M_PI) / (2 * M));
if (u == 0 && v == 0) {
new_img(x, y) /= N;
} else if (u == 0 || v == 0) {
new_img(x, y) /= sqrt(2) / N;
} else {
new_img(x, y) *= 2 / N;
}
}
}
}
}
*img = new_img;
}
static void RunDCTBlockFn(Image<IPixel> *img, int blockSize, DCTBlockFn fn) {
assert (NULL != fn);
assert (0 < blockSize);
assert (static_cast<uint32>(blockSize) < img->GetWidth());
assert (static_cast<uint32>(blockSize) < img->GetHeight());
Image<IPixel> block(blockSize, blockSize);
for (unsigned int j = 0; j < img->GetHeight(); j += blockSize) {
for (unsigned int i = 0; i < img->GetWidth(); i += blockSize) {
@ -660,8 +709,8 @@ extern void DiscreteCosineXForm(Image<IPixel> *img, int blockSize) {
}
}
// Transform it
DCT(&block);
// Run the function
fn(&block);
// Put it back in the original image
for (int y = 0; y < blockSize; ++y) {
@ -684,5 +733,12 @@ extern void DiscreteCosineXForm(Image<IPixel> *img, int blockSize) {
}
}
void DiscreteCosineXForm(Image<IPixel> *img, int blockSize) {
RunDCTBlockFn(img, blockSize, DCT);
}
void InvDiscreteCosineXForm(Image<IPixel> *img, int blockSize) {
RunDCTBlockFn(img, blockSize, IDCT);
}
} // namespace FasTC

35
Base/test/TestImage.cpp
View File

@ -211,3 +211,38 @@ TEST(Image, SplitImage) {
}
}
}
TEST(Image, DCT) {
const uint32 w = 32;
const uint32 h = 32;
FasTC::Image<FasTC::IPixel> img(w, h);
for (uint32 j = 0; j < h; ++j) {
for (uint32 i = 0; i < w; ++i) {
img(i, j) = static_cast<FasTC::IPixel>(i + j);
// img(i, j) = static_cast<FasTC::IPixel>(1);
}
}
FasTC::Image<FasTC::IPixel> orig(img);
// Make sure that taking the DCT and inverse DCT returns
// the same image...
FasTC::DiscreteCosineXForm(&img, 8);
// First make sure they're different
for (uint32 j = 0; j < h; ++j) {
for (uint32 i = 0; i < w; ++i) {
EXPECT_NE(img(i, j), orig(i, j));
}
}
FasTC::InvDiscreteCosineXForm(&img, 8);
for (uint32 j = 0; j < h; ++j) {
for (uint32 i = 0; i < w; ++i) {
EXPECT_NEAR(img(i, j), orig(i, j), 1e-5);
}
}
}