如何从RGBA图像创建ARGB图像
如何从RGBA图像创建ARGB图像
提问于 2014-04-22 18:53:03
我用这个来制作我的申请的视频
我现在用
glReadPixels(x, y, width, height, GL_RGBA, GL_UNSIGNED_BYTE, data);读取帧缓冲区，然后使用
-(UIImage *) createARGBImageFromRGBAImage: (UIImage*)image
{
CGSize dimensions = [image size];
NSUInteger bytesPerPixel = 4;
NSUInteger bytesPerRow = bytesPerPixel * dimensions.width;
NSUInteger bitsPerComponent = 8;
unsigned char *rgba = malloc(bytesPerPixel * dimensions.width * dimensions.height);
unsigned char *argb = malloc(bytesPerPixel * dimensions.width * dimensions.height);
CGColorSpaceRef colorSpace = NULL;
CGContextRef context = NULL;
colorSpace = CGColorSpaceCreateDeviceRGB();
context = CGBitmapContextCreate(rgba, dimensions.width, dimensions.height, bitsPerComponent, bytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrderDefault); // kCGBitmapByteOrder32Big
CGContextDrawImage(context, CGRectMake(0, 0, dimensions.width, dimensions.height), [image CGImage]);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
for (int x = 0; x < dimensions.width; x++) {
for (int y = 0; y < dimensions.height; y++) {
NSUInteger offset = ((dimensions.width * y) + x) * bytesPerPixel;
argb[offset + 0] = rgba[offset + 3];
argb[offset + 1] = rgba[offset + 0];
argb[offset + 2] = rgba[offset + 1];
argb[offset + 3] = rgba[offset + 2];
}
}
colorSpace = CGColorSpaceCreateDeviceRGB();
context = CGBitmapContextCreate(argb, dimensions.width, dimensions.height, bitsPerComponent, bytesPerRow, colorSpace, kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrderDefault); // kCGBitmapByteOrder32Big
CGImageRef imageRef = CGBitmapContextCreateImage(context);
image = [UIImage imageWithCGImage: imageRef];
CGImageRelease(imageRef);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
free(rgba);
free(argb);
return image;
}进行转换，但它看起来很慢。
建议一些更快的方法
回答 1
Stack Overflow用户
回答已采纳
发布于 2014-10-01 20:01:57
#import <Accelerate/Accelerate.h> ////import into your class file.
-(UIImage *) createARGBImageFromRGBAImage: (UIImage*)image
{ //CGSize size = CGSizeMake(320, 480);
CGSize dimensions = CGSizeMake(320, 480);
NSUInteger bytesPerPixel = 4;
NSUInteger bytesPerRow = bytesPerPixel * dimensions.width;
NSUInteger bitsPerComponent = 8;
unsigned char *rgba = malloc(bytesPerPixel * dimensions.width * dimensions.height);
unsigned char *argb = malloc(bytesPerPixel * dimensions.width * dimensions.height);
CGColorSpaceRef colorSpace = NULL;
CGContextRef context = NULL;
colorSpace = CGColorSpaceCreateDeviceRGB();
context = CGBitmapContextCreate(rgba, dimensions.width, dimensions.height, bitsPerComponent, bytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrderDefault); // kCGBitmapByteOrder32Big
CGContextDrawImage(context, CGRectMake(0, 0, dimensions.width, dimensions.height), [image CGImage]);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
const vImage_Buffer src = { rgba, dimensions.height, dimensions.width, bytesPerRow };
const vImage_Buffer dis = { rgba, dimensions.height, dimensions.width, bytesPerRow };
const uint8_t map[4] = {3,0,1,2};
vImagePermuteChannels_ARGB8888(&src, &dis, map, kvImageNoFlags);
/*for (int x = 0; x < dimensions.width; x++) {
for (int y = 0; y < dimensions.height; y++) {
NSUInteger offset = ((dimensions.width * y) + x) * bytesPerPixel;
argb[offset + 0] = rgba[offset + 3];
argb[offset + 1] = rgba[offset + 0];
argb[offset + 2] = rgba[offset + 1];
argb[offset + 3] = rgba[offset + 2];
}
}*/
colorSpace = CGColorSpaceCreateDeviceRGB();
context = CGBitmapContextCreate(dis.data, dimensions.width, dimensions.height, bitsPerComponent, bytesPerRow, colorSpace, kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrderDefault); // kCGBitmapByteOrder32Big
CGImageRef imageRef = CGBitmapContextCreateImage(context);
image = [UIImage imageWithCGImage: imageRef];
CGImageRelease(imageRef);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
free(rgba);
free(argb);
return image;
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/23227904
复制相关文章
相似问题
腾讯云开发者
