#289, #493: Finally implemented subsampling for < 8 bit samples

2026-04-30 00:00:01 -04:00 · 2019-08-29 19:06:05 +02:00
parent a5def1ba3d
commit 0c2433dc9f
4 changed files with 263 additions and 20 deletions
@@ -0,0 +1,145 @@
+package com.twelvemonkeys.imageio.util;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertArrayEquals;
+
+/**
+ * IIOUtilTest
+ */
+public class IIOUtilTest {
+
+    @Test
+    public void subsampleRowPeriod2Byte() {
+        int period = 2;
+
+        byte[] input = {-1, 0, (byte) 0xAA, 0, -1};
+        byte[] output = new byte[divCeil(input.length, period)];
+        byte[] expected = {-1, (byte) 0xAA, -1};
+
+        IIOUtil.subsampleRow(input, 0, input.length, output, 0, 1, 8, period);
+
+        assertArrayEquals(expected, output);
+    }
+
+    @Test
+    public void subsampleRowPeriod2ByteStride3() {
+        int period = 2;
+
+        byte[] input = {-1, -1, -1, 0, 0, 0, (byte) 0xAA, (byte) 0xAA, (byte) 0xAA, 0, 0, 0, -1, -1, -1};
+        byte[] output = new byte[9];
+        byte[] expected = {-1, -1, -1, (byte) 0xAA, (byte) 0xAA, (byte) 0xAA, -1, -1, -1};
+
+        IIOUtil.subsampleRow(input, 0, input.length / 3, output, 0, 3, 8, period);
+
+        assertArrayEquals(expected, output);
+    }
+
+    @Test
+    public void subsampleRowPeriod2Byte1() {
+        int period = 2;
+
+        byte[] input = {(byte) 0xaa, (byte) 0xaa, (byte) 0xaa};
+        byte[] output = new byte[divCeil(input.length, period)];
+        byte[] expected = {(byte) 0xff, (byte) 0xf0};
+
+        IIOUtil.subsampleRow(input, 0, input.length * 8, output, 0, 1, 1, period);
+
+        assertArrayEquals(expected, output);
+    }
+
+    @Test
+    public void subsampleRowPeriod3_1Bit() {
+        int period = 3;
+
+        byte[] input = {(byte) 0x92, (byte) 0x49, (byte) 0x24};
+        byte[] output = new byte[divCeil(input.length, period)];
+        byte[] expected = {(byte) 0xff};
+
+        IIOUtil.subsampleRow(input, 0, input.length * 8, output, 0, 1, 1, period);
+
+        assertArrayEquals(expected, output);
+    }
+
+    @Test
+    public void subsampleRowPeriod2_2Bit() {
+        int period = 2;
+
+        byte[] input = {(byte) 0xcc, (byte) 0xcc, (byte) 0xcc};
+        byte[] output = new byte[divCeil(input.length, period)];
+        byte[] expected = {(byte) 0xff, (byte) 0xf0};
+
+        IIOUtil.subsampleRow(input, 0, input.length * 4, output, 0, 1, 2, period);
+
+        assertArrayEquals(expected, output);
+    }
+
+    @Test
+    public void subsampleRowPeriod2_4Bit() {
+        int period = 2;
+
+        byte[] input = {(byte) 0xf0, (byte) 0xf0, (byte) 0xf0};
+        byte[] output = new byte[divCeil(input.length, period)];
+        byte[] expected = {(byte) 0xff, (byte) 0xf0};
+
+        IIOUtil.subsampleRow(input, 0, input.length * 2, output, 0, 1, 4, period);
+
+        assertArrayEquals(expected, output);
+    }
+
+    @Test
+    public void subsampleRowPeriod2_1Bit2Samples() {
+        int period = 2;
+
+        byte[] input = {(byte) 0xcc, (byte) 0xcc, (byte) 0xcc};
+        byte[] output = new byte[divCeil(input.length, period)];
+        byte[] expected = {(byte) 0xff, (byte) 0xf0};
+
+        IIOUtil.subsampleRow(input, 0, input.length * 4, output, 0, 2, 1, period);
+
+        assertArrayEquals(expected, output);
+    }
+
+    @Test
+    public void subsampleRowPeriod2_2Bit2Samples() {
+        int period = 2;
+
+        byte[] input = {(byte) 0xf0, (byte) 0xf0, (byte) 0xf0};
+        byte[] output = new byte[divCeil(input.length, period)];
+        byte[] expected = {(byte) 0xff, (byte) 0xf0};
+
+        IIOUtil.subsampleRow(input, 0, input.length * 2, output, 0, 2, 2, period);
+
+        assertArrayEquals(expected, output);
+    }
+
+    @Test
+    public void subsampleRowPeriod2_4Bit2Samples() {
+        int period = 2;
+
+        byte[] input = {-1, 0, (byte) 0xAA, 0, -1};
+        byte[] output = new byte[divCeil(input.length, period)];
+        byte[] expected = {-1, (byte) 0xAA, -1};
+
+        IIOUtil.subsampleRow(input, 0, input.length, output, 0, 2, 4, period);
+
+        assertArrayEquals(expected, output);
+    }
+
+    @Test
+    public void subsampleRowPeriod2_1BitOffset1() {
+        int period = 2;
+
+        byte[] input = {(byte) 0xaa, (byte) 0xaa, (byte) 0xaa};
+        byte[] output = new byte[divCeil(input.length, period)];
+        byte[] expected = {(byte) 0xff, (byte) 0xf0};
+
+        IIOUtil.subsampleRow(input, 1, input.length * 8, output, 0, 1, 1, period);
+
+        assertArrayEquals(expected, output);
+    }
+
+    private int divCeil(int numerator, int denominator) {
+        return (numerator + denominator - 1) / denominator;
+    }
+}