Question

我很难找到来自自定义查找表的静态图像的GPUImageLookFilter的真实示例用法。

根据我从互联网上收集到的内容，我发现了这个提议：

    // The original image that should receive the filter
    GPUImagePicture *stillImageSource = [[GPUImagePicture alloc] initWithImage:self.image];

    // The image containing the lookup table (LUT) like https://github.com/BradLarson/GPUImage/blob/master/framework/Resources/lookup_amatorka.png
    GPUImagePicture *lookupImageSource = [[GPUImagePicture alloc] initWithImage:[UIImage imageNamed:@"LUT1.png"]];

    // From now on I don't really understand what's going on
    GPUImageLookupFilter *lookupFilter = [[GPUImageLookupFilter alloc] init];
    [stillImageSource addTarget:lookupFilter];
    [lookupImageSource addTarget:lookupFilter];

    [stillImageSource useNextFrameForImageCapture];
    [stillImageSource processImage];
    [lookupImageSource useNextFrameForImageCapture];
    [lookupImageSource processImage];

    // This is always nil
    UIImage *filteredimage = [lookupFilter imageFromCurrentFramebuffer];

所以如果有人可以写一个完全正常工作的例子，我会非常感激，它使用最新版本和GPUImage框架（撰写本文时为0.1.6）和/或作出解释为如何应工作。

Answer 1

-useNextFrameForImageCapture只能在您要从中提取图像的目标过滤器上调用，而不是其他内容。在上面，你在输入上调用它，而不是输出。

您需要将其修改为以下内容：

stillImageSource addTarget:lookupFilter];
[lookupImageSource addTarget:lookupFilter];

[lookupFilter useNextFrameForImageCapture];
[stillImageSource processImage];
[lookupImageSource processImage];

lookupFilter是你从中获取UIImage的东西，因此需要通知你将要从中捕获它。通过调用processImage上传两个GPUImagePicture来源启动处理，因此-useNextFrameForImageCapture调用需要先于这些来源。

Answer 2

GPUImagePicture *stillImageSource = [[GPUImagePicture alloc] initWithImage:self.image];

GPUImagePicture *lookupImageSource = [[GPUImagePicture alloc] initWithImage:[UIImage imageNamed:@"LUT1.png"]];

GPUImageLookupFilter *lookupFilter = [[GPUImageLookupFilter alloc] init];
[stillImageSource addTarget:lookupFilter];
[lookupImageSource addTarget:lookupFilter];

[stillImageSource useNextFrameForImageCapture];
[stillImageSource processImage];
[lookupImageSource processImage];

UIImage *filteredimage = [lookupFilter imageFromCurrentFramebuffer];

GPUImageLookupFilter无法正常工作

2 个答案: