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Questions tagged [alpha-transparency]

The alpha transparency of an image defines how transparent the pixels of this image are. Typically, each pixel has an alpha value between 0 (fully transparent) and 255 (fully opaque).

Alpha transparency is an attribute of pixels within an image (or image layer) which determines how transparent the pixel is, by blending the pixel color with the color of the pixel in the layer beneath it. most image editing software allow to edit a layer or image alpha transparency. The alpha value is saved in addition to the RGB value of the pixel. Ranges of transparency may change according to the software setup.

Alpha Transparency as part of Alpha Compositing.

468 questions
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OpenGL alpha blending inside an transparent object

I have encountered a problem when simulation transparency in OpenGL. Here is the scenario: I have a ship which is represented by a sphere. Now I though about adding a shield around the ship. I chose a sphere too, but with a larger radius and set the…
Dan Lincan
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Convert FLV video with alpha channel to PNGs with transparency

I have some FLV videos with alpha channels, and I want to convert each of them to PNG images using ffmpeg but keep the transparency. So far, I've tried this: ffmpeg -i input.flv -an -y %d.png But this outputs the PNG files with black background. Is…
Zack
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How to render transparent video in WPF

I am creating an app with WPF and I need to render a video with transparent background. Does anyone know of a tool or way to do it efficiently? As far as I know WPF does not natively support rendering videos with transparent background or alpa…
Pedro _F.M
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Using an alpha transparent mask on a QWidget?

Is it possible to assign an alpha-transparent mask to a QWidget? I know how to set a mask using setMask but it seems it only supports black&white masks. Is it possible to make it support a true alpha channel? i.e. currently I have a PNG like…
laurent
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trying display an image on a transparent window using UpdateLayeredWindow method

I'm trying to create a function to render a text from font atlas and display it on screen using UpdateLayeredWindow method. I'm pretty new to C and WINAPI, could someone help me out and tell me why the UpdateLayeredWindow is failing here. I have…
Aliza
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Unusual result when merging two transparent images in php

Im wondering if I'm doing something wrong, or if this is as good a result as im going to get. Both PNGs on the left are 95x111. The image of the robot has a 5px or so padding of transparent pixels around it, but it seems to be causing problems when…
Dave Chenell
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Vertical stripes on alpha channel PNGs when scaling in Safari on iPhone/iPad

In Safari on iPhone/iPad, when I use two fingers to zoom webpages that have PNGs with an alpha channel, there are obvious renderings errors (vertical stripes) at certain zoom levels. Does anyone know workarounds for this? Original:…
forthrin
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Transparent video in Android AR Scene

I am looking to solve the problem of displaying a transparent video in the AR scenes using Unity ARFoundation and Android platform. I mean, accurately with a simple effect presented for the iOS platform:…
Artik
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Why does this code make the QImage lose its alpha channel?

I'm trying to understand why the code below changes the QImage in Qt. It's not meant to do anything (yet), it's just for testing. When I run the code on an image with alpha, the alpha channel is lost and replaced by a black background. QImage…
laurent
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Convert images to alpha transparency with PHP

$im = imagecreatefrompng('./test.png'); $white = imagecolorallocate($im, 255, 255, 255); imagecolortransparent($im, $white); This code is fine for removing pure white from an image, but I what I want to do is convert all colors to alpha…
Tim
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How to cut out a rectangle (i.e. set it transparent) in imagemagick?

I combine three files, the 2nd and 3rd having some transparent areas, into one and this works fine: convert image1.png image2.png image3.png -flatten image_combined.png In addition to combining those pictures, I would like to cut out a rectangle in…
Belmex
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Strange strips while drawing transparent things in OpenGL

I'm using per-pixel linked lists to realize order-independent transparency in OpenGL. But while I drawn something, something looks strange happened. The following picture shows the non-transparent mode, and everything looks normal. The following…
Ray
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How to continuously vary transparency?

Suppose we create a colored band in R: library(ggplot2) dev.new(width=6, height=3) ggplot(data.frame(20,20)) + geom_rect(aes(xmin=0, xmax=100, ymin=0, ymax=50), fill="blue") I would like to continuously vary the transparency of the band along…
bluepole
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Different alpha in arrows using quiver on top of rectangle

I have a Rectangle plotted with matplotlib with alpha=0.8 . I can plot a marker with different alpha on it but when i try to set the alpha parameter on the arrows of quiver it seems like it doesn't change. I was wondering if there is a way to set a…
programmer222
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Changing alpha value on top and bottom parts of UIImageView

I'm picking up a photo from the photo albums, however I would like to be able to do the following with it: Change the alpha value of the top and bottom parts (lets say 20 pixles from the top and 20 pixles from the bottom) to 0.5 then copy only the…
AdamSharp
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