Objective-C中框架的水平翻转 [英] Horizontal Flip of a frame in Objective-C

问题描述

我正在尝试为我的程序（流式网络摄像头）创建一个过滤器，使框架水平翻转，使网络摄像头像镜子一样。

I am trying to create a filter for my program (which streams a webcam) which makes the frame flip horizontally, making the webcam act like a mirror.

但是，尽管它可以编译和运行，但过滤器似乎对其没有任何影响。

However, while it compiles and runs, the filter does not seem to have any effect on it.

以下是代码：

CIImage *resultImage = image;
CIFilter *flipFilter = [CIFilter filterWithName:@"CIAffineTransform"];
[flipFilter setValue:resultImage forKey:@"inputTransform"];

NSAffineTransform* flipTransform = [NSAffineTransform transform];
[flipTransform scaleXBy:-1.0 yBy:1.0]; //horizontal flip
[flipFilter setValue:flipTransform forKey:@"inputTransform"];

resultImage = [flipFilter valueForKey:@"outputImage"];

奇怪的是，其他过滤器似乎也起作用。例如：

Strangely enough, other filters appear to work. For example:

CIFilter * ciEffectFilter = [CIFilter filterWithName:@"CIGloom"];
[ciEffectFilter setDefaults];
CIImage *resultImage = image;
[ciEffectFilter setValue: resultImage forKey:@"inputImage"];
[ciEffectFilter setValue:[NSNumber numberWithFloat: 0.75]
                  forKey:@"inputIntensity"];
[ciEffectFilter setValue:[NSNumber numberWithFloat: 20]
                  forKey:@"inputRadius"];
resultImage = [ciEffectFilter valueForKey:@"outputImage"];


CIFilter *ciCropFilter = [CIFilter filterWithName:@"CICrop"];
[ciCropFilter setDefaults];
[ciCropFilter setValue: resultImage forKey:@"inputImage"];
[ciCropFilter setValue: [CIVector vectorWithX:50 Y:50 Z:300 W:
                         300] forKey:@"inputRectangle"];

resultImage = [ciCropFilter valueForKey:@"outputImage"];

与NSAffineTransform有关系吗？我环顾四周，但未找到任何答案。
感谢堆！

Is it something to do with NSAffineTransform? I have looked around, but I have not found any answers. Thanks heaps!

推荐答案

我不确定这是否是问题，但是在您的第一个代码段中，为同一个键设置两个不同的值（您两次设置 inputTransform ），我认为第一个应该是 inputImage 代替。请尝试以下操作：

I'm not sure if this is the problem, but in your first code snippet you are setting two different values for the same key (you set inputTransform twice), I think the first one should be inputImage instead. Try the following instead:

CIImage *resultImage = image;
CIFilter *flipFilter = [CIFilter filterWithName:@"CIAffineTransform"];
[flipFilter setValue:resultImage forKey:@"inputImage"];

NSAffineTransform* flipTransform = [NSAffineTransform transform];
[flipTransform scaleXBy:-1.0 yBy:1.0]; //horizontal flip
[flipFilter setValue:flipTransform forKey:@"inputTransform"];

resultImage = [flipFilter valueForKey:@"outputImage"];

此外，您可能需要按图像的宽度平移X轴

Also, you may need to translate the X axis by the width of the image

[flipTransform translateXBy:... yBy:0];

这篇关于Objective-C中框架的水平翻转的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！