core-image

问题 I'm trying to achieve the same effect that appears when you enter the menu in the Read Dead Redemption (RDR) game: After browsing the CIFilter library I found that the filter I'm looking for is CIColorMonochrome . After applying the filter on a sample image I get the following result: This looks great, however not quite the same effect as in the RDR picture. I'm going to have a number over the image and it needs to be clearly visible. Therefore, I was wondering if the is a filter that will

问题 I'm trying to achieve the same effect that appears when you enter the menu in the Read Dead Redemption (RDR) game: After browsing the CIFilter library I found that the filter I'm looking for is CIColorMonochrome . After applying the filter on a sample image I get the following result: This looks great, however not quite the same effect as in the RDR picture. I'm going to have a number over the image and it needs to be clearly visible. Therefore, I was wondering if the is a filter that will

问题 I'm trying to implement edit image using UIPanGesture, UIRotateGesture, and UIPinchGesture. After editing, I wish to save edited UIImage. I'm done edit image functionality. But I don't know How to save exactly perfect like native iOS Camera App. Pan Gesture is working fine. My problem is Rotate and Scale. How to set center anchor point of UIImage? When I saved UIImage from transform information then the result of UIImage is looks different because Rotate and Scale, then It always applied

问题 I'm working with a CIImage, and while I understand it's not a linear image, it does hold some data. My question is whether or not a CIImage's extent property returns pixels or points? According to the documentation, which says very little, it's working space coordinates. Does this mean there's no way to get the pixels / points from a CIImage and I must convert to a UIImage to use the .size property to get the points? I have a UIImage with a certain size, and when I create a CIImage using the

问题 Does anyone know what the limitations are on image size with custom CIFilters? I've created a filter that performs as expected when the images are up to 2 mega pixels but then produce very strange results when the images are larger. I've tested this both in my cocoa app as well as in quartz composer. The filter I've developed is a geometry-type distortion filter that (I think) requires an ROI and a DOD that spans the entire input image. I've created this filter for remapping panoramic images

问题 I am attempting to understand how CIAdditionCompositing works. As part of my testing, I have created a square mid-gray image: and a square black image: When I combined these two square images using a CIAdditionCompositing patch, I expected to see a gray square whose color matched the original mid-gray square exactly (because all color components of the black image have value 0). However, the final result is actually brighter than the original gray image: I don't understand how this result is

问题 I have an UIImage that I snap from the camera. I want to do some image manipulations so I transform it to a CIImage. CIImage *ciImage = [CIImage imageWithCGImage:snappedImage.CGImage]; Next I do my thing, and then transform it back to a UIImage: UIImage *image = [UIImage imageWithCIImage:ciImage]; If now I want to transform this to data to save it into Core Data for example: NSData *data = UIImagePNGRepresentation(image); the data ends up being nil on iOS 12. (works on iOS 13, same thing

问题 I have an UIImage that I snap from the camera. I want to do some image manipulations so I transform it to a CIImage. CIImage *ciImage = [CIImage imageWithCGImage:snappedImage.CGImage]; Next I do my thing, and then transform it back to a UIImage: UIImage *image = [UIImage imageWithCIImage:ciImage]; If now I want to transform this to data to save it into Core Data for example: NSData *data = UIImagePNGRepresentation(image); the data ends up being nil on iOS 12. (works on iOS 13, same thing

来源： https://stackoverflow.com/questions/64201384/why-does-uigraphicsgetcurrentcontext-return-nil-after-uigraphicsbeginimagecontex

来源： https://stackoverflow.com/questions/64201384/why-does-uigraphicsgetcurrentcontext-return-nil-after-uigraphicsbeginimagecontex