I am attempting to display a video file with transparency inside my application using a transparency key (RGB: 0x00FF00, or full green) using #BradLarson's awesome GPUImage toolkit. However, I am experiencing some difficulties with the GPUImageChromaKeyFilter filter, and I don't quite understand why.
My source video file is available in my dropbox here (12 KB, 3 seconds long, full green background, just a square on the screen),
And I used the sample project titled SimpleVideoFilter.
This is the code I attempted to use (I simply replaced -viewDidLoad):
NSURL *sampleURL = [[NSBundle mainBundle] URLForResource:#"sample" withExtension:#"m4v"];
movieFile = [[GPUImageMovie alloc] initWithURL:sampleURL];
filter = [[GPUImageChromaKeyFilter alloc] init];
[filter setColorToReplaceRed:0 green:1 blue:0];
[filter setEnabled:YES];
[movieFile addTarget:filter];
GPUImageView *filterView = (GPUImageView *)self.view;
[filter addTarget:filterView];
[movieFile startProcessing];
According to the documentation (which is sparse), this should have the effect of replacing all of the green in the video. Instead, I get this as an output:
Which tells me that the video is playing (and thus it's copying to the application), but it doesn't seem to be doing any chroma keying. Why would this be? Do I need to manually set smoothing values & thresholds? I shouldn't, because the source only contains two colors (0x00FF00 and 0x000000).
I have tested this on the device as well, to no avail. Almost all other filters I attempt to use work, such as GPUImageRGBFilter, GPUImageSepiaFilter, etc. Could GPUImageChromaKeyFilter just be broken?
Any help with this would be appreciated, as at this point I'm scraping the bottom of the barrel for transparency on a video.
Similar to the original question, I wanted to put a green-screen video on top of a custom view hierarchy incl. live video. Turned out this was not possible with the standard GPUImage ChromaKey filter(s). Instead of alpha blending, it blended the green pixels with the background pixels. For example a red background became yellow and blue became cyan.
The way to get it working involves two steps:
1) make sure the filterview has a transparent background:
filterView.backgroundColor=[UIColor clearColor];
2) Modify GPUImageChromaKeyFilter.m
old: gl_FragColor = vec4(textureColor.rgb, textureColor.a * blendValue);
new: gl_FragColor = vec4(textureColor.rgb * blendValue, 1.0 * blendValue);
Now all keyed (for example green) pixels in the video become transparent and uncover whatever is below the filterview, incl. (live-)video.
I got it to work by using GPUImageChromaKeyBlendFilter and setting a background image. I'd like to know though if we can do without having to set a background. When I don't set the background, the movie shows as white, but adding the background renders fine...
filter = [[GPUImageChromaKeyBlendFilter alloc] init];
[(GPUImageChromaKeyBlendFilter *)filter setColorToReplaceRed:0.0 green:1.0 blue:0.0];
[(GPUImageChromaKeyBlendFilter *)filter setThresholdSensitivity:0.4];
UIImage *inputImage = [UIImage imageNamed:#"background.png"];
sourcePicture = [[GPUImagePicture alloc] initWithImage:inputImage smoothlyScaleOutput:YES];
[sourcePicture addTarget:filter];
[sourcePicture processImage];
Related
I'm using for the first time the GPUImage framework of Brad Larson.
I don't know if it's possible, but I would like to use the GPUImageChromaKeyFilter and GPUImageSepiaFilter. I can use them separately, but at the same time, it doesn't work.
The sepia tone works, but the chromaKey seems doesn't work.
EDIT 2: WORKING
Here is my code:
- (void)setupCameraAndFilters:(AVCaptureDevicePosition)cameraPostion {
videoCamera = [[GPUImageVideoCamera alloc] initWithSessionPreset:AVCaptureSessionPreset640x480 cameraPosition:cameraPostion];
videoCamera.outputImageOrientation = UIInterfaceOrientationLandscapeRight;
// ChromaKey
chromaKeyFilter = [[GPUImageChromaKeyBlendFilter alloc] init];
[(GPUImageChromaKeyBlendFilter *)chromaKeyFilter setColorToReplaceRed:0.0 green:1.0 blue:0.0];
[videoCamera addTarget:chromaKeyFilter];
// Input image (replace the green background)
UIImage *inputImage;
inputImage = [UIImage imageNamed:#"chromaBackground.jpg"];
sourcePicture = [[GPUImagePicture alloc] initWithImage:inputImage smoothlyScaleOutput:YES];
[sourcePicture processImage];
[sourcePicture addTarget:chromaKeyFilter];
// Sepia filter
sepiaFilter = [[GPUImageSepiaFilter alloc] init];
[chromaKeyFilter addTarget:sepiaFilter];
[sepiaFilter addTarget:self.filteredVideoView];
[videoCamera startCameraCapture];
}
Your problem is that the above code doesn't really make sense. In the first example, you have your still image going into the single-input GPUImageChromaKeyFilter, then you try to target both that source image and your video feed to the single-input GPUImageSepiaFilter. One of those two inputs will be overridden by the other.
GPUImageFilterGroups are merely convenience classes for grouping sequences of filters together an an easy-to-reuse package, and won't solve anything here.
If you're trying to blend video with a chroma-keyed image, you need to use a GPUImageChromaKeyBlendFilter, which takes two inputs and blends them together based on the keying. You can then send that single output image to the sepia tone filter, or however you want to sequence that.
You have to use GPUImageFilterGroup filter in order to accomplish what you want. In the examples of the GPUImage you can find how to achieve this. Good Luck!
I wrote this code to change the brightness of an UIImage via an UISlider and the GPUImageBrightnessFilter. But every time I'll test it the app crashes.
My code:
- (IBAction)sliderBrightness:(id)sender {
CGFloat midpoint = [(UISlider *)sender value];
[(GPUImageTiltShiftFilter *)brightnessFilter setTopFocusLevel:midpoint - 0.1];
[(GPUImageTiltShiftFilter *)brightnessFilter setBottomFocusLevel:midpoint + 0.1];
[sourcePicture processImage];
}
- (void) brightnessFilter {
UIImage *inputImage = imgView.image;
sourcePicture = [[GPUImagePicture alloc] initWithImage:inputImage smoothlyScaleOutput:YES];
brightnessFilter = [[GPUImageTiltShiftFilter alloc] init];
// sepiaFilter = [[GPUImageSobelEdgeDetectionFilter alloc] init];
GPUImageView *imageView = (GPUImageView *)self.view;
[brightnessFilter forceProcessingAtSize:imageView.sizeInPixels]; // This is now needed to make the filter run at the smaller output size
[sourcePicture addTarget:brightnessFilter];
[brightnessFilter addTarget:imageView];
[sourcePicture processImage];
}
Let me make an alternative architectural suggestion. Instead of creating a GPUImagePicture and GPUImageBrightnessFilter each time you change the brightness, then saving that out as a UIImage to a UIImageView, it would be far more efficient to reuse the initial picture and filter and render that to a GPUImageView.
Take a look at what I do in the SimpleImageFilter example that comes with GPUImage. For the tilt-shifted image that's displayed to the screen, I create a GPUImagePicture of the source image once, create one instance of the tilt-shift filter, and then send the output to a GPUImageView. This avoids the expensive (both performance and memory-wise) process of going to a UIImage and then displaying that in a UIImageView, and will be much, much faster. While you're at it, you can use -forceProcessingAtSize: on your filter to only render as many pixels as will be displayed in your final view, also speeding things up.
When you have the right settings for filtering your image, and you want the final UIImage out, you can do one last render pass to extract the processed UIImage. You'd set your forced size back to 0 right before doing that, so you now process the full image.
I've successfully added a crosshair generator and harris corner detection filter onto a GPUImageStillCamera output, as well as on live video from GPUImageVideoCamera.
I'm now trying to get this working on a photo set on a UIImageView, but continually get a black screen as the output. I have been reading the issues listed on GitHub against Brad Larson's GPUImage project, but they seemed to be more in relation to blend type filters, and following the suggestions there I still face the same problem.
I've tried altering every line of code to follow various examples I have seen, and to follow Brad's example code in the Filter demo projects, but the result is always the same.
My current code is, once I've taken a photo (which I check to make sure it is not just a black photo at this point):
GPUImagePicture *stillImageSource = [[GPUImagePicture alloc] initWithImage:self.photoView.image];
GPUImageHarrisCornerDetectionFilter *cornerFilter1 = [[GPUImageHarrisCornerDetectionFilter alloc] init];
[cornerFilter1 setThreshold:0.1f];
[cornerFilter1 forceProcessingAtSize:self.photoView.frame.size];
GPUImageCrosshairGenerator *crossGen = [[GPUImageCrosshairGenerator alloc] init];
crossGen.crosshairWidth = 15.0;
[crossGen forceProcessingAtSize:self.photoView.frame.size];
[cornerFilter1 setCornersDetectedBlock:^(GLfloat* cornerArray, NSUInteger cornersDetected, CMTime frameTime, BOOL endUpdating)
{
[crossGen renderCrosshairsFromArray:cornerArray count:cornersDetected frameTime:frameTime];
}];
[stillImageSource addTarget:crossGen];
[crossGen addTarget:cornerFilter1];
[crossGen prepareForImageCapture];
[stillImageSource processImage];
UIImage *currentFilteredImage = [crossGen imageFromCurrentlyProcessedOutput];
UIImageWriteToSavedPhotosAlbum(currentFilteredImage, nil, nil, nil);
[self.photoView setImage:currentFilteredImage];
I've tried prepareForImageCapture on both filters, on neither, adding the two targets in the opposite order, calling imageFromCurrentlyProcessedOutput on either filter, I've tried it without the crosshair generator, I've tried using local variables and variables declared in the .h file. I've tried with and without forceProcessingAtSize on each of the filters.
I can't think of anything else that I haven't tried to get the output. The app is running on iPhone 7.0, in Xcode 5.0.1. The standard filters work on the photo, e.g. the simple GPUImageSobelEdgeDetectionFilter included in the SimpleImageFilter test app.
Any suggestions? I am saving the output to the camera roll so I can check it's not just me failing to display it correctly. I suspect it's a stupid mistake somewhere but am at a loss as to what else to try now.
Thanks.
Edited to add: the corner detection is definitely working, as depending on the threshold I set, it returns between 6 and 511 corners.
The problem with the above is that you're not chaining filters in the proper order. The Harris corner detector takes in an input image, finds the corners within it, and provides the callback block to return those corners. The GPUImageCrosshairGenerator takes in those points and creates a visual representation of the corners.
What you have in the above code is image->GPUImageCrosshairGenerator-> GPUImageHarrisCornerDetectionFilter, which won't really do anything.
The code in your answer does go directly from the image to the GPUImageHarrisCornerDetectionFilter, but you don't want to use the image output from that. As you saw, it produces an image where the corners are identified by white dots on a black background. Instead, use the callback block, which processes that and returns an array of normalized corner coordinates for you to use.
If you need these to be visible, you could then take that array of coordinates and feed it into the GPUImageCrosshairGenerator to create visible crosshairs, but that image will need to be blended with your original image to make any sense. This is what I do in the FilterShowcase example.
I appear to have fixed the problem, with trying different variations again and now the returned image is black but there are white dots in the locations of the found corners. I removed the GPUImageCrosshairGenerator altogether. The code that got this working was:
GPUImagePicture *stillImageSource = [[GPUImagePicture alloc] initWithImage:self.photoView.image];
GPUImageHarrisCornerDetectionFilter *cornerFilter1 = [[GPUImageHarrisCornerDetectionFilter alloc] init];
[cornerFilter1 setThreshold:0.1f];
[cornerFilter1 forceProcessingAtSize:self.photoView.frame.size];
[stillImageSource addTarget:cornerFilter1];
[cornerFilter1 prepareForImageCapture];
[stillImageSource processImage];
UIImage *currentFilteredImage = [cornerFilter1 imageFromCurrentlyProcessedOutput];
UIImageWriteToSavedPhotosAlbum(currentFilteredImage, nil, nil, nil);
[self.photoView setImage:currentFilteredImage];
I do not need to add the crosshairs for the purpose of my app - I simply want to parse the locations of the corners to provide some cropping, but I required the dots to be visible to check the corners were being detected correctly. I'm not sure if the white dots on black are the expected outcome of this filter, but I presume so.
Updated code for Swift 2:
let stillImageSource: GPUImagePicture = GPUImagePicture(image: image)
let cornerFilter1: GPUImageHarrisCornerDetectionFilter = GPUImageHarrisCornerDetectionFilter()
cornerFilter1.threshold = 0.1
cornerFilter1.forceProcessingAtSize(image.size)
stillImageSource.addTarget(cornerFilter1)
stillImageSource.processImage()
let tmp: UIImage = cornerFilter1.imageByFilteringImage(image)
I would like to create a GPUImageView to display a filter in real time (as opposed to keep reading imageFromCurrentlyProcessedOutput)
Is it possible to use GPUImage's GPUImageChromaKeyBlendFilter with a still source image automatically updating a GPUImageView?
Here is my code reading this into a UIImage;
UIImage *inputImage = [UIImage imageNamed:#"1.JPG"];
UIImage *backgroundImage = [UIImage imageNamed:#"2.JPG"];
GPUImagePicture *stillImageSource = [[GPUImagePicture alloc] initWithImage:inputImage];
GPUImageChromaKeyBlendFilter *stillImageFilter = [[GPUImageChromaKeyBlendFilter alloc] init];
[stillImageFilter setThresholdSensitivity:0.5];
[stillImageFilter setColorToReplaceRed:0.0 green:1.0 blue:0.0];
[stillImageSource addTarget:stillImageFilter];
[stillImageSource processImage];
UIImage *currentFilteredVideoFrame = [stillImageFilter imageByFilteringImage: backgroundImage ];
Everything I have tried so far requires you to add the 'backgroundImage' as a target to the filter (as you would if you were using the StillCamera). If you add the backgroundImage as a target, GPUImage just uses this new images as it's base image.
Can anyone help?
Thanks,
Don't use -imageByFilteringImage: with a two-input filter, like blends. It's a convenience method to quickly set up a small filter chain based on a UIImage and grab a UIImage out. You're not going to want it for something targeting a GPUImageView, anyway.
For the chroma key blend, you'll need to target your input image (the one with the color to be replaced) and background image to the blend, in that order using -addTarget, with GPUImagePicture instances for both. You then target your blend to the GPUImageView.
One note, you'll need to maintain strong references to your GPUImagePictures past the setup method, if you want to keep updating the filter after this point, so you may need to make them instance variables on your controller class.
Once you've set things up in this way, the result will go to your GPUImageView. Every time you call -processImage on one of the two images, the display in your GPUImageView will be updated. Therefore, you can call that after every change in filter settings, like if you had a slider to update filter values, and the image will be updated in realtime.
I am using the GPUImage library and I'm trying to blend two images in realtime, and display them on a GPUImageView. I am trying to alpha-blend plain camera input, with a filtered version of it. Here is what I'm trying to do:
----------------->----v
--camera--| alpha blend ----> image view
-----> color filter --^
I've found some posts about using the blend filters, but they don't seem to be methods for realtime processing. I've found https://github.com/BradLarson/GPUImage/issues/319, GPUImage: blending two images, and https://github.com/BradLarson/GPUImage/issues/751 (but they either aren't for realtime processing, (first and the second), or doesn't work (third one).
I've tried almost everything, but all I'm getting is a white image in the GPUImageView. If I don't use the alpha blend filter, say, just use a false color filter or something similar, it works perfectly. Here is my code:
blendFilter = [[GPUImageAlphaBlendFilter alloc] init];
blendFilter.mix = 0.5;
[blendFilter prepareForImageCapture];
[blendFilter addTarget:imageView];
passThrough = [[GPUImageFilter alloc] init];
[passThrough prepareForImageCapture];
[passThrough addTarget:blendFilter];
selectedFilter = [[GPUImageFalseColorFilter alloc] init];
[selectedFilter prepareForImageCapture];
[selectedFilter addTarget:blendFilter];
stillCamera = [[GPUImageStillCamera alloc] init];
stillCamera.outputImageOrientation = UIInterfaceOrientationPortrait;
[stillCamera addTarget:passThrough];
[stillCamera addTarget:selectedFilter];
[stillCamera startCameraCapture];
All I'm getting is a white, blank screen. If I change [selectedFilter addTarget:blendFilter]; to [selectedFilter addTarget:imageView]; then false color filter gets displayed on the image.
There seems to be something wrong with the alpha blend filter. I've read that in some posts that I need to call processImage on the inputs, but those posts are all for non-realtime inputs as far as I understand. How can I get GPUImageAlphaBlendFilter to work in realtime?
Ok, after investigating the issue further over the internet and on project's issue list (https://github.com/BradLarson/GPUImage/issues) and found a workaround. While setting the blend filter as the target, I needed to specify the texture index specifically. For some reason (probably a bug), adding the target blend filter two times doesn't add the second texture correctly at the next index. So setting the texture indices explicitly as 0 and 1 did work:
[passThrough addTarget:blendFilter atTextureLocation:0];
[selectedFilter addTarget:blendFilter atTextureLocation:1];
For the filters that are targets of single sources, addTarget: is enough though such as [stillCamera addTarget:selectedFilter];.