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Questions tagged [alpha]

An alpha channel determines the transparency of an image or view. Lower values are more transparent, and higher values are more opaque

An alpha channel determines the transparency of an image or view. Lower values are more transparent, and higher values are more opaque

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Imagick ALPHA vs OPACITY

While developping color-extractor I stumbled across a quirk with Imagick. I confirmed the issue with a single black transparent pixel image. Under Gimp this black is shown as 75% opaque so I guess its alpha/transparency is 25%. When I run…
MatTheCat
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C# proper image alpha layer when form is invisible

I'm looking for a way to have images on invisible form that allow alpha transparency and allow to place and use buttons/labels etc. I've tried this Transparent background on winforms?, layered window and many more, nothing fully successful. I've…
erexo
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Change opacity of parent layer without affecting child layer in Swift

I have a UIImage. I am creating a CALayer and adding it to the UIImage layer. I want to change the UImage's layer opacity to 0.5 without affecting the child layer's opacity. In my research it seem snot possible. Is there a workaround?
Kashif
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Can't save image in JPG with white background OpenCV

I write a simple app in OpenCV that delete black background of an image and save it with white background in JPG. However, it's always saved with black background. This is my code: Mat Imgsrc = imread("../temp/temp1.jpg",1) ; mat dest; Mat temp,…
mahdi101
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Changing the alpha of UIView affects the font opacity

Quite simple question: I want to change the opacity of UIView and keep font above it with alpha = 1.0. So as you can see there are two labeles and under them is UIView. I've set the opcaity of the UIView (for example: @IBOutlet weak var coView:…
mikro098
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BufferedImage set alpha from other BufferedImage

I got 3 BufferedImages: A, C and D. All are images with colors and an alpha channel. C has to alpha-over D, but with the transparency layer of A. The idea is to: Set the alpha channel of C to that of A Alpha over them I do the alpha mixing with…
piegames
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Bitmap conversion - Creating a transparent + black image from a B&W source

I have a whole bunch of jpg files that I need to use in a project, that for one reason or another cannot be altered. Each file is similar (handwriting), black pen on white BG. However I need to use these assets against a non-white background in my…
Conor
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ggplot scale alpha continuous fill color

I've tried to create an alpha plot but I couldn't find right way to do it. I tried different combination to figure out and I've almost there but I need a little help. My question is how can I get rid off blue color in the plot. My script is ` p <-…
eabanoz
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Testing point in the alpha channel

Is there a way to detect if the alpha of a pixel after drawing is not 0 when using OpenGLES on the iphone? I would like to test multiple points to see id they are inside the area of a random polygon drawn by the user. If you know Flash, something…
sharvey
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Swift animatewithDuration() instantly completes

So, I have this code: UIView.animate(withDuration: 10.0, delay: 0, options: .curveLinear , animations: { self.gameLabel.alpha = 0 }, completion: nil) The problem is when this code is called it instantly goes to a 0 alpha and doesn't…
Sam Hoffmann
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ImageMagick - flatten of more png images

I have more PNG images (let's say img1.png, img2_transparent.png, img3.png) and I want them flatten to one image. Before I flatten them I set (I want second image was slightly transparent): convert img2_transparent.png -alpha on -channel a -evaluate…
stepan
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Is it possible to retrieve the alpha value of a pixel of a PNG file in the 0-255 range?

In a recent competition I was given the task to extract binary data (another PNG) from a PNG image file's alpha channel. The data was encoded in such a way that if I read the values in the alpha channel for each pixel from the top left (e.g.…
SeinopSys
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BufferedImage loses alpha when passed as a parameter

I'm having a problem where images loaded in as a buffered image contain their alpha channels correctly. But when passed as a parameter the alpha channel is lost. I load the images in like this: MousePointer =…
Timothy Eckstein
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Sorting polygons for correct alpha blending in DirectX 9?

What is the correct way to sort polygons so that they blend properly? The basic concept I think is to render the furthest polygon first back to closest in order. But what about cases of intersecting polygons?
meds
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Why, when displaying a greyscale .png file in Psychtoolbox (with an alpha channel), is the image displaying in bright red?

I am currently preparing some greyscale .png images that will be displayed in Psychtoolbox. These .png files all have transparent backgrounds, and so I've been adding in the alpha layer into the file matrix like so: % sets up for the…
treismanwolfe
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