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asf-gitbox-commits pushed a commit to branch geoapi-4.0
in repository https://gitbox.apache.org/repos/asf/sis.git
The following commit(s) were added to refs/heads/geoapi-4.0 by this push:
new 38bc219527 Build a gray scale instead of index color model when
possible. The use of gray scale allows interpolations, contrarily to index
color model.
38bc219527 is described below
commit 38bc2195273df13aad446f0512939d6632ab5c3e
Author: Martin Desruisseaux <[email protected]>
AuthorDate: Wed Apr 22 18:59:41 2026 +0200
Build a gray scale instead of index color model when possible.
The use of gray scale allows interpolations, contrarily to index color
model.
---
.../image/internal/shared/ColorModelFactory.java | 53 ++++++++++++++-------
.../sis/storage/geotiff/GeoTiffStoreTest.java | 4 +-
.../test/org/apache/sis/storage/geotiff/tiled.tiff | Bin 3882 -> 2334 bytes
.../org/apache/sis/storage/geotiff/untiled.tiff | Bin 2602 -> 1054 bytes
4 files changed, 39 insertions(+), 18 deletions(-)
diff --git
a/endorsed/src/org.apache.sis.feature/main/org/apache/sis/image/internal/shared/ColorModelFactory.java
b/endorsed/src/org.apache.sis.feature/main/org/apache/sis/image/internal/shared/ColorModelFactory.java
index 5bc95fb109..3618a131b6 100644
---
a/endorsed/src/org.apache.sis.feature/main/org/apache/sis/image/internal/shared/ColorModelFactory.java
+++
b/endorsed/src/org.apache.sis.feature/main/org/apache/sis/image/internal/shared/ColorModelFactory.java
@@ -358,23 +358,24 @@ public final class ColorModelFactory {
/*
* If there are no categories, construct a gray scale palette.
*/
- final int categoryCount = pieceStarts.length - 1;
- if (numBands == 1 && categoryCount <= 0) {
- final ColorSpace cs = ColorSpace.getInstance(ColorSpace.CS_GRAY);
- final int[] numBits = {
- DataBuffer.getDataTypeSize(dataType)
- };
- return unique(new ComponentColorModel(cs, numBits, false, true,
Transparency.OPAQUE, dataType));
- }
- /*
- * Interpolates the colors in the color palette. Colors that do not
fall
- * in the range of a category will be set to a transparent color.
- */
final int[] colorMap;
int transparent = -1;
- if (categoryCount <= 0) {
- colorMap = ArraysExt.range(0, 256);
+ if (isGrayScale()) {
+ if (numBands == 1) {
+ final ColorSpace cs =
ColorSpace.getInstance(ColorSpace.CS_GRAY);
+ final int[] numBits = {
+ DataBuffer.getDataTypeSize(dataType)
+ };
+ return unique(new ComponentColorModel(cs, numBits, false,
true, Transparency.OPAQUE, dataType));
+ }
+ colorMap = new int[256];
+ Arrays.setAll(colorMap, (i) -> 0xFF000000 | (i << 24) | (i << 16)
| (i << 8) | i);
} else {
+ /*
+ * Interpolates the colors in the color palette. Colors that do
not fall
+ * in the range of a category will be set to a transparent color.
+ */
+ final int categoryCount = pieceStarts.length - 1;
colorMap = new int[pieceStarts[categoryCount]];
for (int i=0; i<categoryCount; i++) {
final int[] colors = ARGB[i];
@@ -435,8 +436,8 @@ public final class ColorModelFactory {
final boolean hasAlpha, final int transparent)
{
/*
- * No need to scan the ARGB values in search of a transparent pixel;
- * the IndexColorModel constructor does that for us.
+ * No need to scan the ARGB values in search of a transparent pixel
+ * since the `IndexColorModel` constructor does that for us.
*/
final int length = ARGB.length;
if (numBits == 0) {
@@ -567,6 +568,26 @@ public final class ColorModelFactory {
return Math.abs(minimum) < 1 && Math.abs(maximum - (upper - 0.5)) <
1.5;
}
+ /**
+ * Returns whether this factory is building a gray scale color model.
+ * A gray scale color model is preferred to an index color model because
gray scale gives
+ * directly the intensity, while index color model is indirect (need to
lookup in a table).
+ * Therefore, sample values associated to gray scale can be interpolated
while sample values
+ * that are indexes cannot be interpolated easily.
+ */
+ private boolean isGrayScale() {
+ if (ARGB == null) {
+ return true;
+ }
+ switch (ARGB.length) {
+ default: return false;
+ case 0: return true;
+ case 1: break;
+ }
+ final int[] codes = ARGB[0];
+ return codes.length == 2 && codes[0] == 0xFF000000 && codes[1] ==
0xFFFFFFFF;
+ }
+
/**
* Creates a color model for opaque images storing pixels using the given
sample model.
* The color model can have an arbitrary number of bands, but in current
implementation only one band is used.
diff --git
a/endorsed/src/org.apache.sis.storage.geotiff/test/org/apache/sis/storage/geotiff/GeoTiffStoreTest.java
b/endorsed/src/org.apache.sis.storage.geotiff/test/org/apache/sis/storage/geotiff/GeoTiffStoreTest.java
index fd5fe04b1e..5d495e9544 100644
---
a/endorsed/src/org.apache.sis.storage.geotiff/test/org/apache/sis/storage/geotiff/GeoTiffStoreTest.java
+++
b/endorsed/src/org.apache.sis.storage.geotiff/test/org/apache/sis/storage/geotiff/GeoTiffStoreTest.java
@@ -138,7 +138,7 @@ public final class GeoTiffStoreTest extends TestCase {
*/
@Test
public void testWriteUntiled() throws Exception {
- testWrite(UNTILED, new Rectangle(32, 16), null, 2602);
+ testWrite(UNTILED, new Rectangle(32, 16), null, 1054);
}
/**
@@ -149,7 +149,7 @@ public final class GeoTiffStoreTest extends TestCase {
@Test
public void testWriteTiled() throws Exception {
final var tileSize = new Dimension(16, 16); // TIFF tile size must
be multiple of 16.
- testWrite(TILED, new Rectangle(tileSize.width * 3, tileSize.height *
2), tileSize, 3882);
+ testWrite(TILED, new Rectangle(tileSize.width * 3, tileSize.height *
2), tileSize, 2334);
}
/**
diff --git
a/endorsed/src/org.apache.sis.storage.geotiff/test/org/apache/sis/storage/geotiff/tiled.tiff
b/endorsed/src/org.apache.sis.storage.geotiff/test/org/apache/sis/storage/geotiff/tiled.tiff
index 68195c9260..e767da887e 100644
Binary files
a/endorsed/src/org.apache.sis.storage.geotiff/test/org/apache/sis/storage/geotiff/tiled.tiff
and
b/endorsed/src/org.apache.sis.storage.geotiff/test/org/apache/sis/storage/geotiff/tiled.tiff
differ
diff --git
a/endorsed/src/org.apache.sis.storage.geotiff/test/org/apache/sis/storage/geotiff/untiled.tiff
b/endorsed/src/org.apache.sis.storage.geotiff/test/org/apache/sis/storage/geotiff/untiled.tiff
index 451287f5cf..c3146ebafa 100644
Binary files
a/endorsed/src/org.apache.sis.storage.geotiff/test/org/apache/sis/storage/geotiff/untiled.tiff
and
b/endorsed/src/org.apache.sis.storage.geotiff/test/org/apache/sis/storage/geotiff/untiled.tiff
differ
