SGI to WebP Converter
Convert SGI to WebP in your browser. SGI files usually come from SGI IRIX workstations, early 3D and VFX pipelines and old texture libraries; WebP is the better fit for images on websites and in apps. You get a lossy WebP at the quality you choose (lossless under More options), keeping 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
SGI expected · other image formats also work
How to use SGI to WebP
- 1
Add your SGI files: drop them here, choose them, or paste from the clipboard.
- 2
Set the quality. 80 to 85 is visually close to the original for most photos.
- 3
Click Convert. Each file is decoded and encoded in a background thread on this device.
- 4
Download the .webp files one at a time or together as a ZIP.
Why use Aback Images for sgi to webp
Where the WebP goes next
WebP opens in every current browser, Windows, macOS, Android, and recent Photoshop, GIMP and Affinity.
WebP next to SGI
A lossy WebP usually comes out far smaller than the SGI, which stores uncompressed (verbatim) or per-row run-length encoding.
The first lossy pass
The SGI holds 8 or 16 bits per channel with nothing discarded yet. This conversion is the first lossy encode these pixels see, and hard edges and flat colour show it first.
Processed on your device
Your images are decoded, edited and encoded inside this browser tab by Web Workers. Nothing is uploaded to a server.
SGI vs WebP
What changes from SGI to WebP
Encoding: the SGI uses uncompressed (verbatim) or per-row run-length encoding; WebP uses lossy VP8 coding or lossless VP8L, and the download is a lossy WebP at the quality you choose (lossless under More options), keeping transparency.
Bit depth: 8 or 16 bits per channel in the SGI; WebP allows 8 bits per channel, and the WebP written here has 8 bits per channel. 16-bit SGI files are reduced to 8 bits per channel.
Colour: greyscale (.bw), RGB (.rgb) or RGBA (.rgba) in the SGI; WebP supports RGB; lossy WebP stores colour at half resolution (4:2:0), written here as 8-bit sRGB.
Transparency: the SGI stores it as a fourth channel plane; the WebP keeps it as a separate alpha plane, available in lossy as well as lossless files.
Metadata: the SGI can carry only an 80-character image name in the header; WebP can carry EXIF, XMP and ICC chunks, but nothing is copied across.
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.
SGI files usually come from SGI IRIX workstations, early 3D and VFX pipelines and old texture libraries.
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.
When converting SGI to WebP makes sense
WebP is the better choice for images on websites and in apps, while SGI suits legacy SGI and 3D pipelines.
WebP strengths: 25-35% smaller than JPEG; Transparency and animation in one format; Supported by every modern browser. Drawbacks to weigh: Some older desktop apps and photo printers cannot open it; Max 16383 px per side.
Limitations
- Rows are stored bottom-up and channels as separate planes; the decoder reassembles them, so orientation is preserved.
- A few older desktop apps, print services and upload forms still reject WebP; keep a JPG or PNG copy for those.
- WebP images are limited to 16383 pixels on each side.
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Frequently asked questions
Does converting SGI to WebP lose quality?
WebP is lossy, so detail the eye barely notices is discarded to save space. 16-bit SGI files are reduced to 8 bits per channel.
Is transparency kept in the WebP?
Yes. SGI stores it as a fourth channel plane, and the WebP is written with an alpha channel, so transparent areas stay transparent.
What quality should I choose for WebP?
80 to 85 is visually close to the original for most photos. Go lower for thumbnails, or switch on Lossless under More options for screenshots and graphics.
Which apps open WebP files?
Every current browser, Windows, macOS, Android, and recent Photoshop, GIMP and Affinity.
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.