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Fix logic problems with table based grayscale ICC profiles

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White-point was calculated wrongly and some tables could cause bad
behavior in the tables.

Change-Id: I24e8f5f3cc1306f5f898a4acbf7b008e26bd04e2
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
(cherry picked from commit f493d41722fc76a04f699ea26128fdf3d215d913)
This commit is contained in:
Allan Sandfeld Jensen 2021-02-25 12:42:08 +01:00
parent ee2dc9e19d
commit 07a65fecbf
2 changed files with 5 additions and 5 deletions
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8
src/gui/painting/qcolortransfertable_p.h
View File

@ -136,7 +136,7 @@ public:
return 1.0f; return 1.0f;
if (!m_table16.isEmpty()) { if (!m_table16.isEmpty()) {
float v = x * 65535.0f; float v = x * 65535.0f;
uint32_t i = std::floor(resultLargerThan * (m_tableSize - 1)) + 1; uint32_t i = std::floor(resultLargerThan * (m_tableSize - 1));
for ( ; i < m_tableSize; ++i) { for ( ; i < m_tableSize; ++i) {
if (m_table16[i] > v) if (m_table16[i] > v)
break; break;
@ -145,14 +145,14 @@ public:
return 1.0f; return 1.0f;
float y1 = m_table16[i - 1]; float y1 = m_table16[i - 1];
float y2 = m_table16[i]; float y2 = m_table16[i];
Q_ASSERT(x >= y1 && x < y2); Q_ASSERT(v >= y1 && v <= y2);
float fr = (v - y1) / (y2 - y1); float fr = (v - y1) / (y2 - y1);
return (i + fr) * (1.0f / (m_tableSize - 1)); return (i + fr) * (1.0f / (m_tableSize - 1));
} }
if (!m_table8.isEmpty()) { if (!m_table8.isEmpty()) {
float v = x * 255.0f; float v = x * 255.0f;
uint32_t i = std::floor(resultLargerThan * (m_tableSize - 1)) + 1; uint32_t i = std::floor(resultLargerThan * (m_tableSize - 1));
for ( ; i < m_tableSize; ++i) { for ( ; i < m_tableSize; ++i) {
if (m_table8[i] > v) if (m_table8[i] > v)
break; break;
@ -161,7 +161,7 @@ public:
return 1.0f; return 1.0f;
float y1 = m_table8[i - 1]; float y1 = m_table8[i - 1];
float y2 = m_table8[i]; float y2 = m_table8[i];
Q_ASSERT(x >= y1 && x < y2); Q_ASSERT(v >= y1 && v <= y2);
float fr = (v - y1) / (y2 - y1); float fr = (v - y1) / (y2 - y1);
return (i + fr) * (1.0f / (m_tableSize - 1)); return (i + fr) * (1.0f / (m_tableSize - 1));
} }

2
src/gui/painting/qicc.cpp
View File

@ -759,7 +759,7 @@ bool fromIccProfile(const QByteArray &data, QColorSpace *colorSpace)
} else { } else {
colorspaceDPtr->primaries = QColorSpace::Primaries::Custom; colorspaceDPtr->primaries = QColorSpace::Primaries::Custom;
// Calculate chromaticity from xyz (assuming y == 1.0f). // Calculate chromaticity from xyz (assuming y == 1.0f).
float y = 1.0f / (1.0f + whitePoint.z - whitePoint.x); float y = 1.0f / (1.0f + whitePoint.z + whitePoint.x);
float x = whitePoint.x * y; float x = whitePoint.x * y;
QColorSpacePrimaries primaries(QColorSpace::Primaries::SRgb); QColorSpacePrimaries primaries(QColorSpace::Primaries::SRgb);
primaries.whitePoint = QPointF(x,y); primaries.whitePoint = QPointF(x,y);