我知道有 RGB -> Luminance 的公式，但我需要给出一个亮度参数来修改图像的 RGB 值。我怎么做？
谢谢
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7 回答
22
最简单的方法是将每个 R、G、B 值乘以某个常数——如果常数 >1，它会变亮，如果 <1，它会变暗。如果你让它更亮，那么你必须测试每个值以确保它不会超过最大值（通常是 255）。
这不仅比从 RGB 到 HSL 再转换回来更简单，而且它更接近于当你在一个物理对象上照射不同数量的光时会发生什么。
于 2012-06-22T20:57:24.120 回答
19
从RGB映射到HSL（Hue/saturation/luminance），保持色相和饱和度不变，只修改亮度，然后做HSL到RGB的反向映射。
于 2012-06-22T20:29:52.580 回答
4
添加到 Mark Ransom 的答案：最好使用具有 255 常数的所述因子并将其添加到当前颜色值：
float brightnessFac = //between -1.0 and 1.0
byte brightnessRed = red + (255f * brightnessFac);
如果您只使用 0.0 到 1.0 之间的因子
byte brightnessRed = red * brightnessFac;
值 0 保持为零。
于 2014-06-03T18:13:27.060 回答
4
我的建议与ChrisA 相同。的答案，但有一点不同：
请改用HS P颜色空间，因为它是 Photoshop 算法的近似值，并且效果更好。
为了不只是链接到 HSP 的网站（坦率地说应该绰绰有余；只是我不喜欢没有示例的情况下回答），这是我的C#实现，它遵循该网站的：
#region Definitions
//Perceived brightness to Red ratio.
private const double Pr = .299;
//Perceived brightness to Green ratio.
private const double Pg = .587;
//Perceived brightness to Blue ratio.
private const double Pb = .114;
#endregion
//Expected ranges: Hue = 0-359... Other values = 0-1
public static ColorRGB ToRGB(double hue, double saturation, double perceivedBrightness, double alpha) {
//Check values within expected range
hue = hue < 0 ? 0 : hue > 359 ? 359 : hue;
saturation = saturation < 0 ? 0 : saturation > 1 ? 1 : saturation;
perceivedBrightness = perceivedBrightness < 0 ? 0 : perceivedBrightness > 1 ? 1 : perceivedBrightness;
alpha = alpha < 0 ? 0 : alpha > 1 ? 1 : alpha;
//Conversion
var minOverMax = 1 - saturation;
double r, g, b;
if (minOverMax > 0) {
double part;
if (hue < 0.166666666666667D) { //R>G>B
hue = 6 * (hue - 0); part = 1 + hue * (1 / minOverMax - 1);
b = perceivedBrightness / Math.Sqrt(Pr / minOverMax / minOverMax + Pg * part * part + Pb);
r = b / minOverMax; g = b + hue * (r - b);
}
else if (hue < 0.333333333333333D) { //G>R>B
hue = 6 * (-hue + 0.333333333333333D); part = 1 + hue * (1 / minOverMax - 1);
b = perceivedBrightness / Math.Sqrt(Pg / minOverMax / minOverMax + Pr * part * part + Pb);
g = b / minOverMax; r = b + hue * (g - b);
}
else if (hue < 0.5D) { // G>B>R
hue = 6 * (hue - 0.333333333333333D); part = 1 + hue * (1 / minOverMax - 1);
r = perceivedBrightness / Math.Sqrt(Pg / minOverMax / minOverMax + Pb * part * part + Pr);
g = r / minOverMax; b = r + hue * (g - r);
}
else if (hue < 0.666666666666667D) { //B>G>R
hue = 6 * (-hue + 0.666666666666667D); part = 1 + hue * (1 / minOverMax - 1);
r = perceivedBrightness / Math.Sqrt(Pb / minOverMax / minOverMax + Pg * part * part + Pr);
b = r / minOverMax; g = r + hue * (b - r);
}
else if (hue < 0.833333333333333D) { //B>R>G
hue = 6 * (hue - 0.666666666666667D); part = 1 + hue * (1 / minOverMax - 1);
g = perceivedBrightness / Math.Sqrt(Pb / minOverMax / minOverMax + Pr * part * part + Pg);
b = g / minOverMax; r = g + hue * (b - g);
}
else { //R>B>G
hue = 6 * (-hue + 1D); part = 1 + hue * (1 / minOverMax - 1);
g = perceivedBrightness / Math.Sqrt(Pr / minOverMax / minOverMax + Pb * part * part + Pg);
r = g / minOverMax; b = g + hue * (r - g);
}
}
else {
if (hue < 0.166666666666667D) { //R>G>B
hue = 6 * (hue - 0D); r = Math.Sqrt(perceivedBrightness * perceivedBrightness / (Pr + Pg * hue * hue)); g = r * hue; b = 0;
}
else if (hue < 0.333333333333333D) { //G>R>B
hue = 6 * (-hue + 0.333333333333333D); g = Math.Sqrt(perceivedBrightness * perceivedBrightness / (Pg + Pr * hue * hue)); r = g * hue; b = 0;
}
else if (hue < 0.5D) { //G>B>R
hue = 6 * (hue - 0.333333333333333D); g = Math.Sqrt(perceivedBrightness * perceivedBrightness / (Pg + Pb * hue * hue)); b = g * hue; r = 0;
}
else if (hue < 0.666666666666667D) { //B>G>R
hue = 6 * (-hue + 0.666666666666667D); b = Math.Sqrt(perceivedBrightness * perceivedBrightness / (Pb + Pg * hue * hue)); g = b * hue; r = 0;
}
else if (hue < 0.833333333333333D) { //B>R>G
hue = 6 * (hue - 0.666666666666667D); b = Math.Sqrt(perceivedBrightness * perceivedBrightness / (Pb + Pr * hue * hue)); r = b * hue; g = 0;
}
else { //R>B>G
hue = 6 * (-hue + 1D); r = Math.Sqrt(perceivedBrightness * perceivedBrightness / (Pr + Pb * hue * hue)); b = r * hue; g = 0;
}
}
return new ColorRGB(r, g, b, alpha);
}
//Expected ranges: 0-1 on all components
public static ColorHSP FromRGB(double red, double green, double blue, double alpha) {
//Guarantee RGB values are in the correct ranges
red = red < 0 ? 0 : red > 1 ? 1 : red;
green = green < 0 ? 0 : green > 1 ? 1 : green;
blue = blue < 0 ? 0 : blue > 1 ? 1 : blue;
alpha = alpha < 0 ? 0 : alpha > 1 ? 1 : alpha;
//Prepare & cache values for conversion
var max = MathExtensions.Max(red, green, blue);
var min = MathExtensions.Min(red, green, blue);
var delta = max - min;
double h, s, p = Math.Sqrt(0.299 * red + 0.587 * green + 0.114 * blue);
//Conversion
if (delta.Equals(0)) h = 0;
else if (max.Equals(red)) {
h = (green - blue) / delta % 6;
}
else if (max.Equals(green)) h = (blue - red) / delta + 2;
else h = (red - green) / delta + 4;
h *= 60;
if (h < 0) h += 360;
if (p.Equals(0))
s = 0;
else
s = delta / p;
//Result
return new ColorHSP(h, s, p, alpha);
}
于 2017-10-03T20:12:57.993 回答
0
import java.io. * ;
import java.awt.Color;
import javax.imageio.ImageIO;
import java.io. * ;
import java.awt.image.BufferedImage;
class Psp {
public static void main(String a[]) {
try {
File input = new File("abc.jpg");
File output = new File("output1.jpg");
BufferedImage picture1 = ImageIO.read(input); // original
BufferedImage picture2 = new BufferedImage(picture1.getWidth(), picture1.getHeight(), BufferedImage.TYPE_INT_RGB);
int width = picture1.getWidth();
int height = picture1.getHeight();
int factor = 50;
for (int y = 0; y < height; y++) { //loops for images
for (int x = 0; x < width; x++) {
Color c = new Color(picture1.getRGB(x, y));
int r = c.getRed() + factor;
int b = c.getBlue() + factor;
int g = c.getGreen() + factor;
if (r >= 256) {
r = 255;
} else if (r < 0) {
r = 0;
}
if (g >= 256) {
g = 255;
} else if (g < 0) {
g = 0;
}
if (b >= 256) {
b = 255;
} else if (b < 0) {
b = 0;
}
picture2.setRGB(x, y, new Color(r, g, b).getRGB());
}
}
ImageIO.write(picture2, "jpg", output);
} catch(Exception e) {
System.out.println(e);
}
}
}
于 2018-01-04T20:12:14.570 回答
0
你可以试试 LookupTable 和 LookupOp；这样您就可以通过修改 LookupTable 来调整图片的亮度。使图片变亮只是为 RGB 增加一些价值。
BufferedImage dstImage = new BufferedImage(input.getWidth(), input.getHeight(),BufferedImage.TYPE_3BYTE_BGR);
LookupTable lookupTable = new ShortLookupTable(0, data);
LookupOp op = new LookupOp(lookupTable, null);
op.filter(toBeTone, dstImage);
于 2021-07-04T03:14:47.193 回答
-3
调整图像的亮度是可以完成的最简单的图像处理操作之一。所涉及的只是为每个红色、绿色和蓝色分量添加所需的亮度变化。
它会是这样的：
colour = GetPixelColour(x, y)
newRed = Truncate(Red(colour) + brightness)
newGreen = Truncate(Green(colour) + brightness)
newBlue = Truncate(Blue(colour) + brightness)
PutPixelColour(x, y) = RGB(newRed, newGreen, newBlue)
用于确保红色、绿色和蓝色的新值在有效范围内的代码。
Procedure Truncate(value)
If value < 0 Then value = 0
If value > 255 Then value = 255
Return value
EndProcedure
于 2015-02-22T11:58:05.417 回答