I have an image I want to partially mask (wallSprite), an image to act as a mask over it (wallMaskBox), and a node to hold both (wallCropNode). When I simply add both images as children of wallCropNode, both image display correctly:
var wallSprite = SKSpriteNode(imageNamed: "wall.png")
var wallCropNode = SKCropNode()
var wallMaskBox = SKSpriteNode(imageNamed: "blacksquaretiny.png")
wallMaskBox.zPosition = 100
wallCropNode.addChild(wallSprite)
wallCropNode.addChild(wallMaskBox)
gameplayContainerNode.addChild(wallCropNode)
But when I set the mask image as a maskNode property of the crop node:
var wallSprite = SKSpriteNode(imageNamed: "wall.png")
var wallCropNode = SKCropNode()
var wallMaskBox = SKSpriteNode(imageNamed: "blacksquaretiny.png")
wallMaskBox.zPosition = 100
wallCropNode.addChild(wallSprite)
wallCropNode.maskNode = wallMaskBox
gameplayContainerNode.addChild(wallCropNode)
the wallSprite image disappears entirely, instead of being partly cropped. Any ideas?
The issue is your black square image is completely opaque. Some (or all) of its pixels should be transparent (i.e., alpha = 0). The pixels that correspond to the mask node's transparent pixels will be masked out (i.e., not rendered) in the cropped node. To demonstrate this, I used your code to create the following.
Here's the original image:
Here's the mask image that I used for the maskNode. Note that the white regions are transparent (i.e., alpha = 0). From Apple's documentation,
When rendering its children, each pixel is verified against the
corresponding pixel in the mask. If the pixel in the mask has an alpha
value of less than 0.05, the image pixel is masked out. Any pixel not
rendered by the mask node is automatically masked out.
and here's the cropped node. I took a screenshot of the scene from the iPhone 6 simulator.
Related
I am doing some operation where I need to replace the bigger rectangle with the smaller rectangle.
Most answers suggested to use smallerRectMat.copyTo(biggerRectMat) but it didn't give me the require output. The submat is changed but the original image is as it is.
And when I try to see the submat both became same of same smaller rectangle size.
Mat rectNose = testBuffer.submat(rectA.y,rectA.y+rectA.height,rectA.x,rectC.x+rectC.width);
Rect biggerRect = getHeadContour(testBuffer);
Mat rectHead = testBuffer.submat(biggerRect.y+1,biggerRect.y+biggerRect.height,biggerRect.x+1,biggerRect.x+biggerRect.width);
rectNose.copyTo(rectHead);
Imgcodecs.imwrite("/Users/test.jpg",rectHead);
Imgcodecs.imwrite("/Users/test1.jpg",rectNose);
Imgcodecs.imwrite("/Users/test1.jpg",testBuffer);
Basically I want to copy the rectangle near the nose region to the rectangle with blue boundary at forehead.
You can try ROI(Region Of Image) scaling
smallRect = img[rectA.y:rectA.y+rectA.height, rectA.x:rectC.x+rectC.width]
upscaledRegion = cv2.resize(smallRect , (biggerRect.width, biggerRect.height), interpolation=cv2.INTER_AREA)
img[biggerRect.y:biggerRect.y+biggerRect.height, biggerRect.x:biggerRect.x+biggerRect.width] = upscaledRegion
I am trying to use a CALayer with an image as contents for masking a UIView. For the mask I have complex png image. If I apply the image as a view.layer.mask I get the opposite behaviour of what I want.
Is there a way to reverse the CAlayer? Here is my code:
layerMask = CALayer()
guard let layerMask = layerMask else { return }
layerMask.contents = #imageLiteral(resourceName: "mask").cgImage
view.layer.mask = layerMask
// What I would like to to is
view.layer.mask = layerMask.inverse. // <---
I have seen several posts on reverse CAShapeLayers and Mutable paths, but nothing where I can reverse a CALayer.
What I could do is reverse the image in Photoshop so that the alpha is inverted, but the problem with that is that I won't be able to create an image with the exact size to fit all screen sizes. I hope it does make sense.
What I would do is construct the mask in real time. This is easy if you have a black image of the logo. Using standard techniques, you can draw the logo image into an image that you construct in real time, so that you are in charge of the size of the image and the size and placement of logo within it. Using a "Mask To Alpha" CIFilter, you can then convert the black to transparent for use as a layer mask.
So, to illustrate. Here's the background image: this is what we want to see wherever we punch a hole in the foreground:
Here's the foreground image, lying on top of the background and completely hiding it:
Here's the logo, in black (ignore the grey, which represents transparency):
Here's the logo drawn in code into a white background of the correct size:
And finally, here's that same image converted into a mask with the Mask To Alpha CIFilter and attached to the foreground image view as its mask:
Okay, I could have chosen my images a little better, but this is what I had lying around. You can see that wherever there was black in the logo, we are punching a hole in the foreground image and seeing the background image, which I believe is exactly what you said you wanted to do.
The key step is the last one, namely the conversion of the black-on-white image of the logo (im) to a mask; here's how I did that:
let cim = CIImage(image:im)
let filter = CIFilter(name:"CIMaskToAlpha")!
filter.setValue(cim, forKey: "inputImage")
let out = filter.outputImage!
let cgim = CIContext().createCGImage(out, from: out.extent)
let lay = CALayer()
lay.frame = self.iv.bounds
lay.contents = cgim
self.iv.layer.mask = lay
If you're using a CALayer as a mask for another CALayer, you can invert the mask by creating a large opaque layer and subtracting out the mask shape with the xor blend mode.
For example, this code subtracts a given layer from a large opaque layer to create an mask layer:
// Create a large opaque layer to serve as the inverted mask
let largeOpaqueLayer = CALayer()
largeOpaqueLayer.bounds = .veryLargeRect
largeOpaqueLayer.backgroundColor = UIColor.black.cgColor
// Subtract out the mask shape using the `xor` blend mode
let maskLayer = ...
largeOpaqueLayer.addSublayer(maskLayer)
maskLayer.compositingFilter = "xor"
Then you can use that layer as the mask for some other CALayer. For example here I'm using it as the mask of a small blue rectangle:
smallBlueRectangle.mask = largeOpaqueLayer
So you can see the mask is inverted! On the other hand if you just use the un-inverted maskLayer directly as a mask, you can see the mask is not inverted:
I have the following image:
On a UIImageView of the exact same frame size, I want to show everything but the red fill.
let mask = CALayer()
mask.contents = clippingImage.CGImage
self.myImageView.layer.mask = mask
I thought the black color would show through when applied as a mask, but when I set the mask the whole view is cleared. What's happening here?
When creating masks from images, you use the Alpha channel, rather than any RGB channel. Even if your mask is black, you need to set its Alpha value to 0, as the mask pays attention only to Alpha channel. Any by default black is [0,0,0,255] in terms of RGBA. If you load RGB, it will of course convert it into RGBA with A = 1.
I use an image view:
#IBOutlet weak var imageView: UIImageView!
to paint an image and also another image which has been rotated. It turns out that the rotated image has very bad quality. In the following image the glasses in the yellow box are not rotated. The glasses in the red box are rotated by 4.39 degrees.
Here is the code I use to draw the glasses:
UIGraphicsBeginImageContext(imageView.image!.size)
imageView.image!.drawInRect(CGRectMake(0, 0, imageView.image!.size.width, imageView.image!.size.height))
var drawCtxt = UIGraphicsGetCurrentContext()
var glassImage = UIImage(named: "glasses.png")
let yellowRect = CGRect(...)
CGContextSetStrokeColorWithColor(drawCtxt, UIColor.yellowColor().CGColor)
CGContextStrokeRect(drawCtxt, yellowRect)
CGContextDrawImage(drawCtxt, yellowRect, glassImage!.CGImage)
// paint the rotated glasses in the red square
CGContextSaveGState(drawCtxt)
CGContextTranslateCTM(drawCtxt, centerX, centerY)
CGContextRotateCTM(drawCtxt, 4.398 * CGFloat(M_PI) / 180)
var newRect = yellowRect
newRect.origin.x = -newRect.size.width / 2
newRect.origin.y = -newRect.size.height / 2
CGContextAddRect(drawCtxt, newRect)
CGContextSetStrokeColorWithColor(drawCtxt, UIColor.redColor().CGColor)
CGContextSetLineWidth(drawCtxt, 1)
// draw the red rect
CGContextStrokeRect(drawCtxt, newRect)
// draw the image
CGContextDrawImage(drawCtxt, newRect, glassImage!.CGImage)
CGContextRestoreGState(drawCtxt)
How can I rotate and paint the glasses without losing quality or get a distorted image?
You should use UIGraphicsBeginImageContextWithOptions(CGSize size, BOOL opaque, CGFloat scale) to create the initial context. Passing in 0.0 as the scale will default to the scale of the current screen (e.g., 2.0 on an iPhone 6 and 3.0 on an iPhone 6 Plus).
See this note on UIGraphicsBeginImageContext():
This function is equivalent to calling the UIGraphicsBeginImageContextWithOptions function with the opaque parameter set to NO and a scale factor of 1.0.
As others have pointed out, you need to set up your context to allow for retina displays.
Aside from that, you might want to use a source image that is larger than the target display size and scale it down. (2X the pixel dimensions of the target image would be a good place to start.)
Rotating to odd angles is destructive. The graphics engine has to map a grid of source pixels onto a different grid where they don't line up. Perfectly straight lines in the source image are no longer straight in the destination image, etc. The graphics engine has to do some interpolation, and a source pixel might be spread over several pixels, or less than a full pixel, in the destination image.
By providing a larger source image you give the graphics engine more information to work with. It can better slice and dice those source pixels into the destination grid of pixels.
I'm trying to do image masking here is my output and code.
This is my masking reference image(Image size doesn't matter),
mask.png,
This is image on which i'm performing masking,
imggo.png,
This is the Output.
I'm using Swift, Here is my code...
override func viewDidLoad() {
super.viewDidLoad()
var maskRefImg : UIImage? = UIImage(named: "mask.png")
var maskImg :UIImage? = UIImage(named: "imggo.png")
var imgView: UIImageView? = UIImageView(frame: CGRectMake(20, 50, 99, 99))
imgView?.image = maskImage(maskRefImg!, maskImage: maskImg!)
self.view.addSubview(imgView!)
}
func maskImage(image:UIImage,maskImage:UIImage)-> UIImage{
var maskRef:CGImageRef = maskImage.CGImage
var mask:CGImageRef = CGImageMaskCreate(CGImageGetWidth(maskRef), CGImageGetHeight(maskRef), CGImageGetBitsPerComponent(maskRef), CGImageGetBitsPerPixel(maskRef), CGImageGetBytesPerRow(maskRef), CGImageGetDataProvider(maskRef), nil, true)
var masked:CGImageRef = CGImageCreateWithMask(image.CGImage, mask)
return UIImage(CGImage: masked)!
}
So,How can I make Go! image colourful.?
Would anyone provide code.?
You are calling the function maskImage with the wrong order of arguments:
The maskImage function wants the image to mask first, and then the mask. But when you call maskImage(maskRefImg!, maskImage: maskImg!) you have it exactly swapped.
So you need to call maskImage(maskImg!, maskImage: maskRefImg!)
I'm guessing that what you want to have is the tilted rectangle with the word "Go!" and that the result image should be exactly the same size as the mask image.
When you swap the images (as you must), the mask image is scaled to the "Go!" image size. But instead, you probably want the mask image centered over your "Go!" image. So you need to create a new image with the same size as your "Go!" image and draw the mask centered into that temporary image. You then use the temporary image as the actual mask to apply.
The example image when you swap the arguments also shows that the "outside" is also green. This probably because your mask image is transparent there and CGImageMaskCreate converts it to black. But the documentation of CGImageCreateWithMask basically tells you that the created image will blend the "Go!" image so that parts where your mask image is black will have the "Go!" image visible and where your mask image is white it will be transparent.
The step-by-step instructions thus are:
Create a new, temporary image that is of the same size as your input image (the "Go!" image).
Fill it with white.
Draw your mask image centered into the temporary image.
Create the actual mask by calling CGImageMaskCreate with the temporary image.
Call CGImageCreateWithMask with the "Go!" image as first argument and the actual mask we've just created as second argument.
The result might be too big (have a lot of transparency surrounding it). If you don't want that you need to crop the result image (e.g. to the size of your original mask image; make sure to crop to the center).
You can probably skip the CGImageCreateWithMask part if you immediately create the temporary image in the DeviceGray color space, as CGImageCreateWithMask wants the second argument to be an image in this color space. In that case, I suggest you modify your mask.png so it does not contain any transparency: it should be white where it's transparent now.