AlphaConstruct is a lightweight Windows app that reconstructs image transparency from two matching versions of the same image — one captured against a pure black background and one against a pure white background.
I originally created AlphaConstruct for situations where a transparent image cannot be captured or exported directly, but where the background behind it can be controlled. By comparing how the exact same image appears against black and white, AlphaConstruct can reconstruct the transparency of the original image and export the result as a transparent PNG.
This can be useful for UI elements, overlays, graphics, renders, and other visual assets where direct alpha export is unavailable.
Getting Started
AlphaConstruct is available from the Microsoft Store. Simply install the application, and it will automatically receive future updates through the Microsoft Store. No additional configuration is required.
How it works
To reconstruct transparency, AlphaConstruct needs two source images:
- The image captured against a pure white background.
- The exact same image captured against a pure black background.
The foreground content, position, dimensions, and all other visual elements must remain identical between the two images. Only the background color may change.
AlphaConstruct compares the differences between these two images to determine how much of each pixel belongs to the foreground and how much of the background is visible through it. This information is then used to reconstruct the image with an alpha channel.
The resulting image can be exported as a transparent PNG.
Preparing the source images
For the reconstruction to work correctly, you must be able to control the background behind the image you want to reconstruct.
Capture or render the image twice:
- Use a pure white background for the first image.
- Without changing anything else, switch the background to pure black and capture the image again.
Both images must have exactly the same dimensions and the foreground must remain in exactly the same position.
AlphaConstruct cannot reconstruct transparency from two unrelated images or compensate for movement, resizing, lighting changes, animation, or other differences between the two captures.
Loading the source images
Select the image captured against white as the Source file white image and the image captured against black as the Source file black image.
AlphaConstruct supports common image formats and uses the two selected images to generate the reconstructed result.
Linear and sRGB reconstruction
AlphaConstruct generates two versions of the reconstructed image: Linear and sRGB.
The way image values are stored and interpreted can affect the reconstruction. Depending on how the source images were created or captured, one method may reproduce the original appearance more accurately than the other.
You can switch between the Linear and sRGB results in the preview and choose the version that looks best for your source images.
Previewing the result
The reconstructed image is displayed directly inside AlphaConstruct before it is exported.
Use the interactive split preview to compare the Linear and sRGB results directly. Moving the divider makes it easier to inspect differences in colors, edges, semi-transparent areas, and other fine details.
The preview background can also be changed between a transparency checkerboard and a solid background color. This makes it easier to inspect how transparent and semi-transparent areas behave against different backgrounds.
Exporting the image
Choose the reconstruction you want to use and specify the output filename and location.
Regardless of the format of the source images, AlphaConstruct exports the reconstructed image as a PNG containing the reconstructed alpha channel.
Your original source images are never modified.
Limitations
AlphaConstruct can only reconstruct transparency when the same foreground can be captured against both a pure black and a pure white background.
For a correct reconstruction:
- Both source images must have exactly the same dimensions.
- The foreground must be identical in both images.
- The foreground must remain in exactly the same position.
- Nothing may change between the two captures except the background color.
- The backgrounds must be pure black and pure white.
If the content moves, changes, is resized, or is rendered differently between the two captures, the reconstructed result may contain incorrect colors, transparency, or visible artifacts.
AlphaConstruct is therefore intended for situations where you have control over the background used to capture or render the source images. It cannot recover the original transparency from an arbitrary image with an existing background.
Privacy & Security
AlphaConstruct processes images entirely on your own computer.
The application reads the two selected source images to reconstruct transparency and writes the resulting PNG to the selected output location. Your original source images are not modified.
AlphaConstruct does not upload, transmit, or share your images. All processing is performed locally on your computer.
For more information, see the Privacy Policy.
Learn More
AlphaConstruct is an open-source project. While the Microsoft Store is the recommended way to install the application, the complete source code is available on GitHub.
GitHub is also the central place to report bugs, request new features, ask questions, get support, explore the source code, and contribute to the project.