WebP to SGI Converter
Convert WebP to SGI in your browser. WebP files usually come from websites, Chrome's Save image as, CDNs and Android apps; SGI is the better fit for legacy SGI and 3D pipelines. You get an 8-bit run-length encoded SGI image, RGB, or RGBA when there is transparency. Nothing is uploaded.
- Processed locally
- No upload, no wait
- No sign-up
- No watermark
Drop images here
or choose files · paste with Ctrl/⌘ V
WebP expected · other image formats also work
How to use WebP to SGI
- 1
Add your WebP files: drop them here, choose them, or paste from the clipboard.
- 2
There is nothing to tune: the SGI is written losslessly. Resizing and rotating are under More options if you need them.
- 3
Click Convert. Each file is decoded and encoded in a background thread on this device.
- 4
Download the .sgi files one at a time or together as a ZIP.
Why use Aback Images for webp to sgi
Where the SGI goes next
SGI opens in Blender, GIMP, ImageMagick, Nuke, XnView and IrfanView.
SGI next to WebP
The SGI keeps the decoded pixels without lossy compression, so expect it to be larger than the WebP.
No new artefacts
WebP is already lossy, since it stores lossy VP8 coding or lossless VP8L; the SGI keeps the decoded pixels losslessly, so this step adds no compression damage of its own.
Processed on your device
Your images are decoded, edited and encoded inside this browser tab by Web Workers. Nothing is uploaded to a server.
WebP vs SGI
What changes from WebP to SGI
Encoding: the WebP uses lossy VP8 coding or lossless VP8L; SGI uses uncompressed (verbatim) or per-row run-length encoding, and the download is an 8-bit run-length encoded SGI image, RGB, or RGBA when there is transparency.
Bit depth: 8 bits per channel in the WebP; SGI allows 8 or 16 bits per channel, and the SGI written here has 8 bits per channel.
Colour: RGB; lossy WebP stores colour at half resolution (4:2:0) in the WebP; SGI supports greyscale (.bw), RGB (.rgb) or RGBA (.rgba), written here as 8-bit sRGB.
Transparency: the WebP stores it as a separate alpha plane, available in lossy as well as lossless files; the SGI keeps it as a fourth channel plane.
Animation: ANMF frame chunks, each with its own delay and blending; the SGI holds one image, so only the first frame is converted.
Metadata: the WebP can carry EXIF, XMP and ICC chunks; SGI can carry only an 80-character image name in the header, but nothing is copied across.
About WebP
WebP is Google's web image format. It supports lossy and lossless compression, transparency and animation, and is typically 25 to 35 percent smaller than JPEG at the same visual quality.
A WebP is a RIFF file: 'RIFF', a length, 'WEBP', then chunks. A simple lossy file is one VP8 chunk and a lossless one is VP8L; the extended VP8X header announces alpha, animation, ICC, EXIF or XMP chunks.
WebP files usually come from websites, Chrome's Save image as, CDNs and Android apps.
About SGI
SGI (also .rgb, .rgba, .bw) is the native image format of Silicon Graphics IRIX workstations, where much of 1990s 3D graphics and film work was done. It stores each colour channel as its own plane, uncompressed or run-length encoded.
An SGI file starts with the big-endian magic number 474 (01 DA), a storage byte (0 verbatim, 1 RLE), bytes per channel, dimensions and channel count in a 512-byte header. Channels are stored as separate planes and rows run from the bottom of the image up; RLE files add tables of row offsets and lengths.
When converting WebP to SGI makes sense
SGI is the better choice for legacy SGI and 3D pipelines, while WebP suits images on websites and in apps.
SGI strengths: Lossless, with 8 or 16 bits per channel; Alpha channel support; Still read by 3D and VFX tools. Drawbacks to weigh: Obsolete outside legacy pipelines; Weak compression; No browser support.
Limitations
- WebP images saved from websites are often already resized and compressed for the page, so the result cannot be sharper than that copy.
- Blender, GIMP, ImageMagick and Nuke read SGI files, but browsers and most photo apps do not.
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Frequently asked questions
Does converting WebP to SGI lose quality?
SGI is written losslessly, so the pixels are stored exactly as decoded. Artefacts already in the WebP stay, but nothing new is lost.
Is transparency kept in the SGI?
Yes. WebP stores it as a separate alpha plane, available in lossy as well as lossless files, and the SGI is written with an alpha channel, so transparent areas stay transparent.
Will my animated WebP stay animated?
No. SGI holds a single image, so only the first frame is kept. Convert to animated WebP, APNG or GIF to keep the motion, or export every frame with the GIF Frame Extractor.
Which apps open SGI files?
Blender, GIMP, ImageMagick, Nuke, XnView and IrfanView. It does not open in web browsers.
Are my images uploaded anywhere?
No. Processing happens inside your browser with WebAssembly and Web Workers. The site only downloads the app code and codecs; your files never leave your device. You can confirm this with the live upload counter on the tool, or in your browser's network panel.
Can I process many files at once?
Yes. Drop a whole selection or folder. Files are processed in parallel on several worker threads, each result can be downloaded on its own, and everything can be saved as one ZIP.
Is it free? Is there a file limit or watermark?
It is free with no account, no watermark and no daily limit. The only limit is your device's memory: very large images (over roughly 100 megapixels) may be refused to keep the tab from crashing.