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properly implement transfer functions and apply them to the output image

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This commit is contained in:
jbb01 2024-08-12 13:13:39 +02:00
parent b8aae8c2e5
commit 533461204a
12 changed files with 259 additions and 165 deletions
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4
src/main/java/eu/jonahbauer/raytracing/Main.java
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@ -1,9 +1,9 @@
package eu.jonahbauer.raytracing;
import eu.jonahbauer.raytracing.render.ImageFormat;
import eu.jonahbauer.raytracing.render.canvas.Canvas;
import eu.jonahbauer.raytracing.render.canvas.LiveCanvas;
import eu.jonahbauer.raytracing.render.canvas.XYZCanvas;
import eu.jonahbauer.raytracing.render.image.PNGImageWriter;
import eu.jonahbauer.raytracing.render.renderer.SimpleRenderer;
import eu.jonahbauer.raytracing.render.color.ColorSpaces;
import org.jetbrains.annotations.NotNull;
@ -42,7 +42,7 @@ public class Main {
renderer.render(camera, scene, canvas);
System.out.printf("rendering finished after %dms", (System.nanoTime() - time) / 1_000_000);
ImageFormat.PNG.write(canvas, config.path);
PNGImageWriter.sRGB.write(canvas, config.path);
}
private record Config(@NotNull Example example, @NotNull Path path, boolean preview, boolean iterative, boolean parallel, int samples, int depth) {

135
src/main/java/eu/jonahbauer/raytracing/render/ImageFormat.java
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@ -1,135 +0,0 @@
package eu.jonahbauer.raytracing.render;
import eu.jonahbauer.raytracing.render.canvas.Canvas;
import eu.jonahbauer.raytracing.render.color.ColorSpaces;
import org.jetbrains.annotations.NotNull;
import java.io.*;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.zip.CRC32;
import java.util.zip.CheckedOutputStream;
import java.util.zip.DeflaterOutputStream;
public enum ImageFormat {
PPM {
@Override
public void write(@NotNull Canvas image, @NotNull OutputStream out) throws IOException {
try (var writer = new BufferedWriter(new OutputStreamWriter(out, StandardCharsets.US_ASCII))) {
writer.write("P3\n");
writer.write(String.valueOf(image.getWidth()));
writer.write(" ");
writer.write(String.valueOf(image.getHeight()));
writer.write("\n255\n");
for (int y = 0; y < image.getHeight(); y++) {
for (int x = 0; x < image.getWidth(); x++) {
var color = image.getRGB(x, y, ColorSpaces.sRGB);
writer.write(String.valueOf(color.red()));
writer.write(" ");
writer.write(String.valueOf(color.green()));
writer.write(" ");
writer.write(String.valueOf(color.blue()));
writer.write("\n");
}
}
}
}
},
PNG {
private static final byte[] MAGIC = new byte[] { (byte) 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A };
private static final int IHDR_LENGTH = 13;
private static final int IHDR_TYPE = 0x49484452;
private static final int IDAT_TYPE = 0x49444154;
private static final int IEND_TYPE = 0x49454E44;
private static final int IEND_CRC = 0xAE426082;
@Override
public void write(@NotNull Canvas image, @NotNull OutputStream out) throws IOException {
try (var data = new NoCloseDataOutputStream(out); var _ = data.closeable()) {
data.write(MAGIC);
writeIHDR(image, data);
writeIDAT(image, data);
writeIEND(image, data);
}
}
private void writeIHDR(@NotNull Canvas image, @NotNull DataOutputStream data) throws IOException {
data.writeInt(IHDR_LENGTH);
try (
var crc = new CheckedOutputStream(data, new CRC32());
var ihdr = new DataOutputStream(crc)
) {
ihdr.writeInt(IHDR_TYPE);
ihdr.writeInt(image.getWidth()); // image width
ihdr.writeInt(image.getHeight()); // image height
ihdr.writeByte(8); // bit depth
ihdr.writeByte(2); // color type
ihdr.writeByte(0); // compression method
ihdr.writeByte(0); // filter method
ihdr.writeByte(0); // interlace method
ihdr.flush();
data.writeInt((int) crc.getChecksum().getValue());
}
}
private void writeIDAT(@NotNull Canvas image, @NotNull DataOutputStream data) throws IOException {
try (
var baos = new ByteArrayOutputStream();
var crc = new CheckedOutputStream(baos, new CRC32());
var idat = new DataOutputStream(crc)
) {
idat.writeInt(IDAT_TYPE);
try (var deflate = new DataOutputStream(new DeflaterOutputStream(idat))) {
for (int y = 0; y < image.getHeight(); y++) {
deflate.writeByte(0); // filter type
for (int x = 0; x < image.getWidth(); x++) {
var pixel = image.getRGB(x, y, ColorSpaces.sRGB);
deflate.writeByte(pixel.red());
deflate.writeByte(pixel.green());
deflate.writeByte(pixel.blue());
}
}
}
var bytes = baos.toByteArray();
data.writeInt(bytes.length - 4); // don't include type in length
data.write(bytes);
data.writeInt((int) crc.getChecksum().getValue());
}
}
private void writeIEND(@NotNull Canvas image, @NotNull DataOutputStream data) throws IOException {
data.writeInt(0);
data.writeInt(IEND_TYPE);
data.writeInt(IEND_CRC);
}
private static class NoCloseDataOutputStream extends DataOutputStream {
public NoCloseDataOutputStream(OutputStream out) {
super(out);
}
@Override
public void close() {
// do nothing
}
public Closeable closeable() {
return super::close;
}
}
},
;
public void write(@NotNull Canvas image, @NotNull Path path) throws IOException {
try (var out = Files.newOutputStream(path)) {
write(image, out);
}
}
public abstract void write(@NotNull Canvas image, @NotNull OutputStream out) throws IOException;
}

2
src/main/java/eu/jonahbauer/raytracing/render/canvas/LiveCanvas.java
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@ -36,7 +36,7 @@ public final class LiveCanvas implements Canvas {
@Override
public void add(int x, int y, int n, @NotNull SampledSpectrum spectrum, @NotNull SampledWavelengths lambda) {
delegate.add(x, y, n, spectrum, lambda);
var color = ColorRGB.gamma(delegate.getRGB(x, y, cs));
var color = cs.encode(delegate.getRGB(x, y, cs));
var rgb = color.red() << 16 | color.green() << 8 | color.blue();
image.setRGB(x, y, rgb);
}

18
src/main/java/eu/jonahbauer/raytracing/render/color/ColorRGB.java
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@ -58,24 +58,6 @@ public record ColorRGB(double r, double g, double b) implements IVec3<ColorRGB>
);
}
public static @NotNull ColorRGB gamma(@NotNull ColorRGB color) {
return new ColorRGB(gamma(color.r), gamma(color.g), gamma(color.b));
}
public static @NotNull ColorRGB inverseGamma(@NotNull ColorRGB color) {
return new ColorRGB(inverseGamma(color.r), inverseGamma(color.g), inverseGamma(color.b));
}
private static double gamma(double value) {
if (value <= 0.0031308) return 12.92 * value;
return 1.055 * Math.pow(value, 1. / 2.4) - 0.055;
}
private static double inverseGamma(double value) {
if (value <= 0.04045) return value / 12.92;
return Math.pow((value + 0.055) / 1.055, 2.4d);
}
@Override
public @NotNull ColorRGB plus(@NotNull ColorRGB other) {
return new ColorRGB(r + other.r, g + other.g, b + other.b);

22
src/main/java/eu/jonahbauer/raytracing/render/color/ColorSpace.java
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@ -25,16 +25,18 @@ public final class ColorSpace {
private final @NotNull Matrix3 XYZfromRGB;
private final @NotNull Matrix3 RGBfromXYZ;
private final @NotNull SpectrumTable RGBtoSpectrumTable;
private final @NotNull TransferFunction transferFunction;
public ColorSpace(
@NotNull Chromaticity r, @NotNull Chromaticity g, @NotNull Chromaticity b,
@NotNull Spectrum illuminant, @NotNull SpectrumTable table
@NotNull Spectrum illuminant, @NotNull SpectrumTable table, @NotNull TransferFunction transferFunction
) {
this.r = Objects.requireNonNull(r, "r");
this.g = Objects.requireNonNull(g, "g");
this.b = Objects.requireNonNull(b, "b");
this.illuminant = new DenselySampledSpectrum(illuminant);
this.RGBtoSpectrumTable = table;
this.RGBtoSpectrumTable = table; // no null-check
this.transferFunction = transferFunction; // no null-check
this.W = illuminant.toXYZ();
this.w = W.xy();
@ -53,6 +55,10 @@ public final class ColorSpace {
this.RGBfromXYZ = XYZfromRGB.invert();
}
/*
* Conversions
*/
public @NotNull ColorRGB toRGB(@NotNull ColorXYZ xyz) {
var out = RGBfromXYZ.times(xyz.toVec3());
return new ColorRGB(out.x(), out.y(), out.z());
@ -84,6 +90,18 @@ public final class ColorSpace {
}
}
public @NotNull ColorRGB encode(@NotNull ColorRGB rgb) {
return transferFunction.encode(rgb);
}
public @NotNull ColorRGB decode(@NotNull ColorRGB rgb) {
return transferFunction.decode(rgb);
}
/*
* Spectrum
*/
public @NotNull SigmoidPolynomial toPolynomial(@NotNull ColorRGB rgb) {
return RGBtoSpectrumTable.get(new ColorRGB(
Math.max(0, rgb.r()),

6
src/main/java/eu/jonahbauer/raytracing/render/color/ColorSpaces.java
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@ -13,21 +13,21 @@ public final class ColorSpaces {
new Chromaticity(0.6400, 0.3300),
new Chromaticity(0.3000, 0.6000),
new Chromaticity(0.1500, 0.0600),
Spectra.D65, read("sRGB_spectrum.bin")
Spectra.D65, read("sRGB_spectrum.bin"), TransferFunctions.sRGB
);
// P3-D65 (display)
public static final @NotNull ColorSpace DCI_P3 = new ColorSpace(
new Chromaticity(0.680, 0.320),
new Chromaticity(0.265, 0.690),
new Chromaticity(0.150, 0.060),
Spectra.D65, read("DCI_P3_spectrum.bin")
Spectra.D65, read("DCI_P3_spectrum.bin"), TransferFunctions.sRGB
);
// ITU-R Rec BT.2020
public static final @NotNull ColorSpace Rec2020 = new ColorSpace(
new Chromaticity(0.708, 0.292),
new Chromaticity(0.170, 0.797),
new Chromaticity(0.131, 0.046),
Spectra.D65, read("Rec2020_spectrum.bin")
Spectra.D65, read("Rec2020_spectrum.bin"), null
);
private static @NotNull SpectrumTable read(@NotNull String name) {

8
src/main/java/eu/jonahbauer/raytracing/render/color/TransferFunction.java Normal file
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@ -0,0 +1,8 @@
package eu.jonahbauer.raytracing.render.color;
import org.jetbrains.annotations.NotNull;
public interface TransferFunction {
@NotNull ColorRGB decode(@NotNull ColorRGB rgb);
@NotNull ColorRGB encode(@NotNull ColorRGB rgb);
}

50
src/main/java/eu/jonahbauer/raytracing/render/color/TransferFunctions.java Normal file
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@ -0,0 +1,50 @@
package eu.jonahbauer.raytracing.render.color;
import org.jetbrains.annotations.NotNull;
public final class TransferFunctions {
public static final @NotNull TransferFunction sRGB = new ComponentTransferFunction() {
@Override
protected double encode(double value) {
if (value <= 0.0031308) return 12.92 * value;
return 1.055 * Math.pow(value, 1. / 2.4) - 0.055;
}
@Override
protected double decode(double value) {
if (value <= 0.04045) return value / 12.92;
return Math.pow((value + 0.055) / 1.055, 2.4d);
}
};
public static final @NotNull TransferFunction LINEAR = new TransferFunction() {
@Override
public @NotNull ColorRGB encode(@NotNull ColorRGB rgb) {
return rgb;
}
@Override
public @NotNull ColorRGB decode(@NotNull ColorRGB rgb) {
return rgb;
}
};
private TransferFunctions() {
throw new UnsupportedOperationException();
}
private abstract static class ComponentTransferFunction implements TransferFunction {
@Override
public final @NotNull ColorRGB decode(@NotNull ColorRGB rgb) {
return new ColorRGB(decode(rgb.r()), decode(rgb.g()), decode(rgb.b()));
}
@Override
public final @NotNull ColorRGB encode(@NotNull ColorRGB rgb) {
return new ColorRGB(encode(rgb.r()), encode(rgb.g()), encode(rgb.b()));
}
protected abstract double encode(double value);
protected abstract double decode(double value);
}
}

19
src/main/java/eu/jonahbauer/raytracing/render/image/ImageWriter.java Normal file
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@ -0,0 +1,19 @@
package eu.jonahbauer.raytracing.render.image;
import eu.jonahbauer.raytracing.render.canvas.Canvas;
import org.jetbrains.annotations.NotNull;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.file.Files;
import java.nio.file.Path;
public interface ImageWriter {
default void write(@NotNull Canvas image, @NotNull Path path) throws IOException {
try (var out = Files.newOutputStream(path)) {
write(image, out);
}
}
void write(@NotNull Canvas canvas, @NotNull OutputStream out) throws IOException;
}

107
src/main/java/eu/jonahbauer/raytracing/render/image/PNGImageWriter.java Normal file
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@ -0,0 +1,107 @@
package eu.jonahbauer.raytracing.render.image;
import eu.jonahbauer.raytracing.render.canvas.Canvas;
import eu.jonahbauer.raytracing.render.color.ColorSpace;
import eu.jonahbauer.raytracing.render.color.ColorSpaces;
import org.jetbrains.annotations.NotNull;
import java.io.*;
import java.util.Objects;
import java.util.zip.CRC32;
import java.util.zip.CheckedOutputStream;
import java.util.zip.DeflaterOutputStream;
public class PNGImageWriter implements ImageWriter {
public static final @NotNull PNGImageWriter sRGB = new PNGImageWriter(ColorSpaces.sRGB);
private static final byte[] MAGIC = new byte[] { (byte) 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A };
private static final int IHDR_LENGTH = 13;
private static final int IHDR_TYPE = 0x49484452;
private static final int IDAT_TYPE = 0x49444154;
private static final int IEND_TYPE = 0x49454E44;
private static final int IEND_CRC = 0xAE426082;
private final @NotNull ColorSpace cs;
public PNGImageWriter(@NotNull ColorSpace cs) {
this.cs = Objects.requireNonNull(cs, "cs");
}
@Override
public void write(@NotNull Canvas image, @NotNull OutputStream out) throws IOException {
try (var data = new NoCloseDataOutputStream(out); var _ = data.closeable()) {
data.write(MAGIC);
writeIHDR(image, data);
writeIDAT(image, data);
writeIEND(image, data);
}
}
private void writeIHDR(@NotNull Canvas image, @NotNull DataOutputStream data) throws IOException {
data.writeInt(IHDR_LENGTH);
try (
var crc = new CheckedOutputStream(data, new CRC32());
var ihdr = new DataOutputStream(crc)
) {
ihdr.writeInt(IHDR_TYPE);
ihdr.writeInt(image.getWidth()); // image width
ihdr.writeInt(image.getHeight()); // image height
ihdr.writeByte(8); // bit depth
ihdr.writeByte(2); // color type
ihdr.writeByte(0); // compression method
ihdr.writeByte(0); // filter method
ihdr.writeByte(0); // interlace method
ihdr.flush();
data.writeInt((int) crc.getChecksum().getValue());
}
}
private void writeIDAT(@NotNull Canvas image, @NotNull DataOutputStream data) throws IOException {
try (
var baos = new ByteArrayOutputStream();
var crc = new CheckedOutputStream(baos, new CRC32());
var idat = new DataOutputStream(crc)
) {
idat.writeInt(IDAT_TYPE);
try (var deflate = new DataOutputStream(new DeflaterOutputStream(idat))) {
for (int y = 0; y < image.getHeight(); y++) {
deflate.writeByte(0); // filter type
for (int x = 0; x < image.getWidth(); x++) {
var pixel = cs.encode(image.getRGB(x, y, cs));
deflate.writeByte(pixel.red());
deflate.writeByte(pixel.green());
deflate.writeByte(pixel.blue());
}
}
}
var bytes = baos.toByteArray();
data.writeInt(bytes.length - 4); // don't include type in length
data.write(bytes);
data.writeInt((int) crc.getChecksum().getValue());
}
}
private void writeIEND(@NotNull Canvas image, @NotNull DataOutputStream data) throws IOException {
data.writeInt(0);
data.writeInt(IEND_TYPE);
data.writeInt(IEND_CRC);
}
private static class NoCloseDataOutputStream extends DataOutputStream {
public NoCloseDataOutputStream(OutputStream out) {
super(out);
}
@Override
public void close() {
// do nothing
}
public Closeable closeable() {
return super::close;
}
}
}

46
src/main/java/eu/jonahbauer/raytracing/render/image/PPMImageWriter.java Normal file
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@ -0,0 +1,46 @@
package eu.jonahbauer.raytracing.render.image;
import eu.jonahbauer.raytracing.render.canvas.Canvas;
import eu.jonahbauer.raytracing.render.color.ColorSpace;
import eu.jonahbauer.raytracing.render.color.ColorSpaces;
import org.jetbrains.annotations.NotNull;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.nio.charset.StandardCharsets;
import java.util.Objects;
public class PPMImageWriter implements ImageWriter {
public static final PPMImageWriter sRGB = new PPMImageWriter(ColorSpaces.sRGB);
private final @NotNull ColorSpace cs;
public PPMImageWriter(@NotNull ColorSpace cs) {
this.cs = Objects.requireNonNull(cs, "cs");
}
@Override
public void write(@NotNull Canvas image, @NotNull OutputStream out) throws IOException {
try (var writer = new BufferedWriter(new OutputStreamWriter(out, StandardCharsets.US_ASCII))) {
writer.write("P3\n");
writer.write(String.valueOf(image.getWidth()));
writer.write(" ");
writer.write(String.valueOf(image.getHeight()));
writer.write("\n255\n");
for (int y = 0; y < image.getHeight(); y++) {
for (int x = 0; x < image.getWidth(); x++) {
var color = cs.encode(image.getRGB(x, y, cs));
writer.write(String.valueOf(color.red()));
writer.write(" ");
writer.write(String.valueOf(color.green()));
writer.write(" ");
writer.write(String.valueOf(color.blue()));
writer.write("\n");
}
}
}
}
}

7
src/main/java/eu/jonahbauer/raytracing/render/texture/ImageTexture.java
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@ -19,22 +19,21 @@ public final class ImageTexture implements Texture {
private final int height;
private final @NotNull Spectrum[][] spectra;
public ImageTexture(@NotNull BufferedImage image, @NotNull ColorSpace cs, @NotNull Spectrum.Type type, boolean gamma) {
public ImageTexture(@NotNull BufferedImage image, @NotNull ColorSpace cs, @NotNull Spectrum.Type type) {
this.width = image.getWidth();
this.height = image.getHeight();
this.spectra = new Spectrum[height][width];
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++) {
var rgb = new ColorRGB(image.getRGB(x, y));
if (gamma) rgb = ColorRGB.inverseGamma(rgb);
var rgb = cs.decode(new ColorRGB(image.getRGB(x, y)));
spectra[y][x] = cs.toSpectrum(rgb, type);
}
}
}
public ImageTexture(@NotNull String path, @NotNull ColorSpace cs) {
this(read(path), cs, Spectrum.Type.ALBEDO, true);
this(read(path), cs, Spectrum.Type.ALBEDO);
}
private static @NotNull BufferedImage read(@NotNull String path) {