Files
unity/crnlib/crn_dxt_hc.h
T
Alexander Suvorov 660322d3a6 Add compression support for ETC1S/ETC2AS encodings
Explanation:

ETC1S encoding is a subset of ETC1, which is using only one color endpoint per 4x4 block. The base color is therefore is always encoded as RGB555 and there is no need to encode block flips. ETC2AS encoding is a subset of ETC2A encoding which is using ETC1S encoding for color and default ETC2A encoding for alpha.

ETC1S/ETC2AS Crunch compression and decompression is based on ETC and DXT Crunch compression and decompression algorithms:
- ETC1S/ETC2AS tiling is performed within the area of 8x8 pixels using DXT1/DXT5 tiling scheme
- ETC1S color endpoints are generated using standard ETC1 optimization
- ETC1S color codebook encoding is equivalent to ETC1 codebook encoding
- ETC1S level encoding is equivalent to DXT1 level encoding
- ETC2AS alpha codebook encoding is equivalent to ETC2A alpha codebook encoding
- ETC2AS level encoding is equivalent to DXT5 level encoding

Testing results suggest that ETC1S/ETC2AS encodings can be used to achieve lower bitrates than ETC1/ETC2A on the Kodak test set while providing equivalent image quality (estimated using PSNR).

DXT Testing:

The modified algorithm has been tested on the Kodak test set using 64-bit build with default settings (running on Windows 10, i7-4790, 3.6GHz). All the decompressed test images are identical to the images being compressed and decompressed using original version of Crunch (revision ea9b8d8).

[Compressing Kodak set without mipmaps using DXT1 encoding]
Original: 1582222 bytes / 28.854 sec
Modified: 1468204 bytes / 5.473 sec
Improvement: 7.21% (compression ratio) / 81.03% (compression time)

[Compressing Kodak set with mipmaps using DXT1 encoding]
Original: 2065243 bytes / 36.925 sec
Modified: 1914805 bytes / 7.297 sec
Improvement: 7.28% (compression ratio) / 80.24% (compression time)

ETC Testing:

The modified algorithm has been tested on the Kodak test set using 64-bit build with default settings (running on Windows 10, i7-4790, 3.6GHz). The ETC1 quantization parameters have been selected in such a way, so that ETC1 compression gives approximately the same average Luma PSNR as the corresponding DXT1 compression (which is equal to 34.044 dB for the Kodak test set compressed without mipmaps using DXT1 encoding and default quality settings).

[Compressing Kodak set without mipmaps using ETC1 encoding]
Total size: 1607858 bytes
Total time: 12.842 sec
Average bitrate: 1.363 bpp
Average Luma PSNR: 34.050 dB

ETCS Testing:

The modified algorithm has been tested on the Kodak test set using 64-bit build with default settings (running on Windows 10, i7-4790, 3.6GHz). The ETC1S quantization parameters have been selected in such a way, so that ETC1S compression gives approximately the same average Luma PSNR as the corresponding DXT1 compression (which is equal to 34.044 dB for the Kodak test set compressed without mipmaps using DXT1 encoding and default quality settings).

[Compressing Kodak set without mipmaps using ETC1S encoding]
Total size: 1363676 bytes
Total time: 15.586 sec
Average bitrate: 1.156 bpp
Average Luma PSNR: 34.047 dB
2018-06-07 19:20:30 +02:00

214 lines
6.2 KiB
C++

// File: crn_dxt_hc.h
// See Copyright Notice and license at the end of inc/crnlib.h
#pragma once
#include "crn_dxt1.h"
#include "crn_dxt5a.h"
#include "crn_dxt_endpoint_refiner.h"
#include "crn_image.h"
#include "crn_dxt.h"
#include "crn_image.h"
#include "crn_dxt_hc_common.h"
#include "crn_tree_clusterizer.h"
#include "crn_threading.h"
#define CRN_NO_FUNCTION_DEFINITIONS
#include "../inc/crnlib.h"
namespace crnlib {
const uint cTotalCompressionPhases = 25;
class dxt_hc {
public:
dxt_hc();
~dxt_hc();
struct endpoint_indices_details {
union {
struct {
uint16 color;
uint16 alpha0;
uint16 alpha1;
};
uint16 component[3];
};
uint8 reference;
endpoint_indices_details() { utils::zero_object(*this); }
};
struct selector_indices_details {
union {
struct {
uint16 color;
uint16 alpha0;
uint16 alpha1;
};
uint16 component[3];
};
selector_indices_details() { utils::zero_object(*this); }
};
struct tile_details {
crnlib::vector<color_quad_u8> pixels;
float weight;
vec<6, float> color_endpoint;
vec<2, float> alpha_endpoints[2];
uint16 cluster_indices[3];
};
crnlib::vector<tile_details> m_tiles;
uint m_num_tiles;
float m_color_derating[cCRNMaxLevels][8];
float m_alpha_derating[8];
float m_uint8_to_float[256];
color_quad_u8 (*m_blocks)[16];
uint m_num_blocks;
crnlib::vector<float> m_block_weights;
crnlib::vector<uint8> m_block_encodings;
crnlib::vector<uint64> m_block_selectors[3];
crnlib::vector<uint32> m_color_selectors;
crnlib::vector<uint64> m_alpha_selectors;
crnlib::vector<bool> m_color_selectors_used;
crnlib::vector<bool> m_alpha_selectors_used;
crnlib::vector<uint> m_tile_indices;
crnlib::vector<endpoint_indices_details> m_endpoint_indices;
crnlib::vector<selector_indices_details> m_selector_indices;
struct params {
params()
: m_num_blocks(0),
m_num_levels(0),
m_num_faces(0),
m_format(cDXT1),
m_perceptual(true),
m_hierarchical(true),
m_color_endpoint_codebook_size(3072),
m_color_selector_codebook_size(3072),
m_alpha_endpoint_codebook_size(3072),
m_alpha_selector_codebook_size(3072),
m_adaptive_tile_color_psnr_derating(2.0f),
m_adaptive_tile_alpha_psnr_derating(2.0f),
m_adaptive_tile_color_alpha_weighting_ratio(3.0f),
m_debugging(false),
m_pProgress_func(0),
m_pProgress_func_data(0) {
m_alpha_component_indices[0] = 3;
m_alpha_component_indices[1] = 0;
for (uint i = 0; i < cCRNMaxLevels; i++) {
m_levels[i].m_first_block = 0;
m_levels[i].m_num_blocks = 0;
m_levels[i].m_block_width = 0;
}
}
uint m_num_blocks;
uint m_num_levels;
uint m_num_faces;
struct {
uint m_first_block;
uint m_num_blocks;
uint m_block_width;
float m_weight;
} m_levels[cCRNMaxLevels];
dxt_format m_format;
bool m_perceptual;
bool m_hierarchical;
uint m_color_endpoint_codebook_size;
uint m_color_selector_codebook_size;
uint m_alpha_endpoint_codebook_size;
uint m_alpha_selector_codebook_size;
float m_adaptive_tile_color_psnr_derating;
float m_adaptive_tile_alpha_psnr_derating;
float m_adaptive_tile_color_alpha_weighting_ratio;
uint m_alpha_component_indices[2];
task_pool* m_pTask_pool;
bool m_debugging;
crn_progress_callback_func m_pProgress_func;
void* m_pProgress_func_data;
};
void clear();
bool compress(
color_quad_u8 (*blocks)[16],
crnlib::vector<endpoint_indices_details>& endpoint_indices,
crnlib::vector<selector_indices_details>& selector_indices,
crnlib::vector<uint32>& color_endpoints,
crnlib::vector<uint32>& alpha_endpoints,
crnlib::vector<uint32>& color_selectors,
crnlib::vector<uint64>& alpha_selectors,
const params& p
);
private:
params m_params;
uint m_num_alpha_blocks;
bool m_has_color_blocks;
bool m_has_etc_color_blocks;
bool m_has_subblocks;
enum {
cColor = 0,
cAlpha0 = 1,
cAlpha1 = 2,
cNumComps = 3
};
struct color_cluster {
color_cluster() : first_endpoint(0), second_endpoint(0) {}
crnlib::vector<uint> blocks[3];
crnlib::vector<color_quad_u8> pixels;
uint first_endpoint;
uint second_endpoint;
color_quad_u8 color_values[4];
};
crnlib::vector<color_cluster> m_color_clusters;
struct alpha_cluster {
alpha_cluster() : first_endpoint(0), second_endpoint(0) {}
crnlib::vector<uint> blocks[3];
crnlib::vector<color_quad_u8> pixels;
uint first_endpoint;
uint second_endpoint;
uint alpha_values[8];
bool refined_alpha;
uint refined_alpha_values[8];
};
crnlib::vector<alpha_cluster> m_alpha_clusters;
crn_thread_id_t m_main_thread_id;
bool m_canceled;
task_pool* m_pTask_pool;
int m_prev_phase_index;
int m_prev_percentage_complete;
vec<6, float> palettize_color(color_quad_u8* pixels, uint pixels_count);
vec<2, float> palettize_alpha(color_quad_u8* pixels, uint pixels_count, uint comp_index);
void determine_tiles_task(uint64 data, void* pData_ptr);
void determine_tiles_task_etc(uint64 data, void* pData_ptr);
void determine_color_endpoint_codebook_task(uint64 data, void* pData_ptr);
void determine_color_endpoint_codebook_task_etc(uint64 data, void* pData_ptr);
void determine_color_endpoint_clusters_task(uint64 data, void* pData_ptr);
void determine_color_endpoints();
void determine_alpha_endpoint_codebook_task(uint64 data, void* pData_ptr);
void determine_alpha_endpoint_clusters_task(uint64 data, void* pData_ptr);
void determine_alpha_endpoints();
void create_color_selector_codebook_task(uint64 data, void* pData_ptr);
void create_color_selector_codebook();
void create_alpha_selector_codebook_task(uint64 data, void* pData_ptr);
void create_alpha_selector_codebook();
bool update_progress(uint phase_index, uint subphase_index, uint subphase_total);
};
} // namespace crnlib