从CIImage创建UIImage [英] Creating UIImage from CIImage

问题描述

我正在使用一些CoreImage过滤器来处理图像。将滤镜应用于输入图像会产生一个名为filterOutputImage的输出图像，类型为CIImage。

I am using some CoreImage filters to process an image. Applying the filter to my input image results in an output image called filterOutputImage of type CIImage.

我现在希望显示该图像，并尝试执行以下操作：

I now wish to display that image, and tried doing:

self.modifiedPhoto = [UIImage imageWithCIImage:filterOutputImage];
self.photoImageView.image = self.modifiedPhoto;

视图为空白 - 没有显示任何内容。

The view however is blank - nothing is being displayed.

如果我添加了打印出有关filterOutputImage和self.modifiedPhoto的详细信息的日志语句，那些日志语句会向我显示这些变量似乎都包含合法的图像数据：它们的大小正在报告且对象不是零。

If I add logging statements that print out details about both filterOutputImage and self.modifiedPhoto, those logging statements are showing me that both those vars appear to contain legitimate image data: their size is being reported and the objects are not nil.

因此，在做了一些谷歌搜索后，我找到了一个需要通过CGImage阶段的解决方案; vis：

So after doing some Googling, I found a solution that requires going through a CGImage stage; vis:

CGImageRef outputImageRef = [context createCGImage:filterOutputImage fromRect:[filterOutputImage extent]];
self.modifiedPhoto = [UIImage imageWithCGImage:outputImageRef scale:self.originalPhoto.scale orientation:self.originalPhoto.imageOrientation];
self.photoImageView.image = self.modifiedPhoto;
CGImageRelease(outputImageRef);

第二种方法有效：我在视图中显示正确的图像。

This second approach works: I am getting the correct image displayed in the view.

有人可以向我解释为什么我的第一次尝试失败了吗？我使用imageWithCIImage方法做错了什么导致图像看起来存在但无法显示？是否总是需要通过CGImage阶段才能从CIImage生成UIImage？

Can someone please explain to me why my first attempt failed? What am I doing wrong with the imageWithCIImage method that is resulting in an image that seems to exist but can't be displayed? Is it always necessary to "pass through" a CGImage stage in order to generate a UIImage from a CIImage?

希望有人能解决我的困惑：）

Hoping someone can clear up my confusion :)

H。

推荐答案

我假设 self.photoImageView 是UIImageView吗？ 如果是这样，最终，它将在UIImage上调用 - [UIImage CGImage] ，然后将该CGImage作为内容传递 CALayer的财产。

I assume that self.photoImageView is a UIImageView? If so, ultimately, it is going to call -[UIImage CGImage] on the UIImage and then pass that CGImage as the contents property of a CALayer.

（见评论：我的详细信息错误）

(See comments: my details were wrong)

根据的UIImage文档 - [UIImage CGImage] ：

If the UIImage object was initialized using a CIImage object, the
value of the property is NULL.

因此UIImageView调用-CGImage，但结果为NULL，因此不会显示任何内容。

So the UIImageView calls -CGImage, but that results in NULL, so nothing is displayed.

我没试过这个，但是你可以尝试制作一个自定义的UIView然后使用UIImage的 -draw ... 中的方法 - [UIView drawRect：] 绘制CIImage。

I haven't tried this, but you could try making a custom UIView and then using UIImage's -draw... methods in -[UIView drawRect:] to draw the CIImage.

这篇关于从CIImage创建UIImage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！