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Use block encoding to store intermediate selectors after endpoint quantization

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This change simplifies further modification of the code.

Explanation:
This change is required for further optimization of the quantization code.

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.

[Compressing Kodak set without mipmaps]
Original: 1582222 bytes / 28.935 sec
Modified: 1494501 bytes / 24.528 sec
Improvement: 5.54% (compression ratio) / 15.23% (compression time)

[Compressing Kodak set with mipmaps]
Original: 2065243 bytes / 36.982 sec
Modified: 1945365 bytes / 32.308 sec
Improvement: 5.80% (compression ratio) / 12.64% (compression time)
This commit is contained in:
Alexander Suvorov
2017-05-18 13:44:04 +02:00
parent 1ef829ed6f
commit b8349dfac8
7 changed files with 208 additions and 196 deletions
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crnlib/crn_dxt5a.cpp
+4
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@@ -46,6 +46,7 @@ bool dxt5_endpoint_optimizer::compute(const params& p, results& r) {
if (m_unique_values.size() == 1) {
r.m_block_type = 0;
r.m_reordered = false;
r.m_error = 0;
r.m_first_endpoint = m_unique_values[0];
r.m_second_endpoint = m_unique_values[0];
@@ -101,6 +102,7 @@ bool dxt5_endpoint_optimizer::compute(const params& p, results& r) {
}
}
m_pResults->m_reordered = false;
if (m_pResults->m_first_endpoint == m_pResults->m_second_endpoint) {
for (uint i = 0; i < m_best_selectors.size(); i++)
m_best_selectors[i] = 0;
@@ -112,11 +114,13 @@ bool dxt5_endpoint_optimizer::compute(const params& p, results& r) {
if (m_pResults->m_first_endpoint > m_pResults->m_second_endpoint) {
utils::swap(m_pResults->m_first_endpoint, m_pResults->m_second_endpoint);
m_pResults->m_reordered = true;
for (uint i = 0; i < m_best_selectors.size(); i++)
m_best_selectors[i] = g_six_alpha_invert_table[m_best_selectors[i]];
}
} else if (!(m_pResults->m_first_endpoint > m_pResults->m_second_endpoint)) {
utils::swap(m_pResults->m_first_endpoint, m_pResults->m_second_endpoint);
m_pResults->m_reordered = true;
for (uint i = 0; i < m_best_selectors.size(); i++)
m_best_selectors[i] = g_eight_alpha_invert_table[m_best_selectors[i]];
}