Start with the stored image inventory
A Source 1 desktop VTF can contain more than one image. Animated textures hold frames, and mipmaps store progressively smaller versions for use at different viewing sizes. This desk reads the supported header and resource ranges before decoding a chosen image. It does not identify the largest image by guessing where the file ends.
Choose your VTF with output frame 0 and PNG mip 0, then run the tool. Both indices are zero-based. For an 8 by 4 texture with four mip levels, the sizes are 8 by 4, 4 by 2, 2 by 1 and 1 by 1. The byte map lists every stored frame/mip pair, including offsets and encoded lengths. Small block-compressed mips still occupy at least one compression block.
Compare transparency with the underlying RGB
Use the preview frame and mip selectors to inspect other stored images without changing the completed download. Choose Original decoded pixels to bypass your edit recipe, or Edited recipe to apply the same settings to the inspected image. The checkerboard helps distinguish partial transparency from dark or pale pixels.
RGB, ignore alpha displays color that may be hidden under a zero alpha value. Alpha grayscale turns the alpha channel into an opaque grayscale image: black means zero, white means 255. These diagnostic views are not a simulation of a Source shader. A material can interpret alpha as a mask or another parameter, so the texture alone cannot establish its final in-game appearance.
Export the image you actually intend
The main PNG download contains the selected input-form frame and mip after your edits, with RGBA pixels preserved. Download preview PNG instead saves the channels currently displayed in the preview. If you select Alpha grayscale, that preview download is an alpha visualization, not the original color texture.
To change the main PNG or VTF selection, change the input form and run again. Preserve the original VTF before handing a converted image to another editor. The desk supports listed uncompressed and DXT codecs in desktop VTF 7.0 through 7.5; console textures, Source 2 files, cubemaps, volume textures, palette and HDR formats are outside this workflow. A successful pixel decode does not certify compatibility with every game branch.