在 Photoshop 中有几种混合模式,例如:
- 颜色加深
- 相乘
- 变暗
- 减轻
- 叠加
(更多信息在这里:http://help.adobe.com/en_US/photoshop/cs/using/WSfd1234e1c4b69f30ea53e41001031ab64-77eba.html)
例如,对于模式Color Burn“查看每个 channel 中的颜色信息并通过增加两者之间的对比度使基色变暗以反射(reflect)混合色。与白色混合不会产生任何变化".
这是我的代码:
Bitmap blendBitmap = BitmapFactory.decodeStream(ctx.getAssets().open(filename));
Canvas canvas = new Canvas(srcBitmap);
canvas.drawBitmap(blendBitmap, 0, 0, null); // ?
p.recycle();
p = null;
是否可以应用 Color Burn 混合模式,而不是简单地将图像绘制在其他图像之上(就像在这个小代码中一样)?
最佳答案
这并不难。
我使用 NDK(因为性能)来处理像素。混合模式的信息非常有用:How does photoshop blend two images together?
我最终的解决方案是:
#define ChannelBlend_ColorBurn(A, B) ((uint8_t) ((B == 0) ? B : max(0, (255 - ((255 -
#define ChannelBlend_Alpha(A, B, O) ((uint8_t) (O * A + (1 - O) * B))
#define ChannelBlend_AlphaF(A, B, F, O) (ChannelBlend_Alpha(F(A, B), A, O))
typedef struct {
uint8_t red;
uint8_t green;
uint8_t blue;
uint8_t alpha;
} rgba;
// Blend
JNIEXPORT void
JNICALL Java_com_package_Filter_jniBlend(JNIEnv* env, jobject obj, jobject bitmapA,
jobject bitmapB, jobject bitmapOut, jint mode) {
// Properties
AndroidBitmapInfo infoA;
void* pixelsA;
AndroidBitmapInfo infoB;
void* pixelsB;
AndroidBitmapInfo infoOut;
void* pixelsOut;
int ret;
// Get image info
if ((ret = AndroidBitmap_getInfo(env, bitmapA, &infoA)) < 0 ||
(ret = AndroidBitmap_getInfo(env, bitmapB, &infoB)) < 0 ||
(ret = AndroidBitmap_getInfo(env, bitmapOut, &infoOut)) < 0) {
return;
}
// Check image
if (infoA.format != ANDROID_BITMAP_FORMAT_RGBA_8888 ||
infoB.format != ANDROID_BITMAP_FORMAT_RGBA_8888 ||
infoOut.format != ANDROID_BITMAP_FORMAT_RGBA_8888) {
return;
}
// Lock all images
if ((ret = AndroidBitmap_lockPixels(env, bitmapA, &pixelsA)) < 0 ||
(ret = AndroidBitmap_lockPixels(env, bitmapB, &pixelsB)) < 0 ||
(ret = AndroidBitmap_lockPixels(env, bitmapOut, &pixelsOut)) < 0) {
LOGE("Error! %d", ret);
}
int h = infoA.height;
int w = infoA.width;
int wh = w * h;
int n;
rgba* inputA = (rgba*) pixelsA;
rgba* inputB = (rgba*) pixelsB;
rgba* output = (rgba*) pixelsOut;
rgba pA, pB;
int x, y;
for (y = 0; y < h; y++) {
for (x = 0; x < w; x++) {
n = y * w + x;
pA = inputA[n];
pB = inputB[n];
float alpha = (float) pB.alpha / 255.0;
output[n].red = ChannelBlend_AlphaF(pA.red, pB.red, ChannelBlend_ColorBurn, alpha);
output[n].green = ChannelBlend_AlphaF(pA.green, pB.green, ChannelBlend_ColorBurn, alpha);
output[n].blue = ChannelBlend_AlphaF(pA.blue, pB.blue, ChannelBlend_ColorBurn, alpha);
}
}
// Unlocks everything
AndroidBitmap_unlockPixels(env, bitmapA);
AndroidBitmap_unlockPixels(env, bitmapB);
AndroidBitmap_unlockPixels(env, bitmapOut);
}
提高性能的小评论:在我对单个像素进行方程式之后,最好将值存储在某种缓存中,以便下次无需方程式即可更快地访问它。
关于android - PNG 混合模式,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/13561507/