PNG to SGI Converter
Convert PNG to SGI in your browser. PNG files usually come from screenshots, design exports, logos and web graphics; 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
PNG expected · other image formats also work
How to use PNG to SGI
- 1
Add your PNG 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 png to sgi
Where the SGI goes next
SGI opens in Blender, GIMP, ImageMagick, Nuke, XnView and IrfanView.
SGI next to PNG
Both sides are lossless, so the size depends on how well the SGI encoder handles this picture compared with the PNG's lossless DEFLATE with a prediction filter chosen per row.
Written without a lossy pass
The SGI is written losslessly, so the pixels decoded from the PNG arrive unchanged, apart from precision beyond 8 bits per channel.
Processed on your device
Your images are decoded, edited and encoded inside this browser tab by Web Workers. Nothing is uploaded to a server.
PNG vs SGI
What changes from PNG to SGI
Encoding: the PNG uses lossless DEFLATE with a prediction filter chosen per row; 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: 1, 2, 4, 8 or 16 bits per channel in the PNG; SGI allows 8 or 16 bits per channel, and the SGI written here has 8 bits per channel. 16-bit PNGs from photo and scientific software are reduced to 8 bits per channel.
Colour: RGB, greyscale, or an indexed palette of up to 256 colours in the PNG; SGI supports greyscale (.bw), RGB (.rgb) or RGBA (.rgba), written here as 8-bit sRGB.
Transparency: the PNG stores it as a full alpha channel, so edges and shadows can fade smoothly; the SGI keeps it as a fourth channel plane.
Metadata: the PNG can carry text chunks, an ICC profile, physical resolution and EXIF in an eXIf chunk; SGI can carry only an 80-character image name in the header, but nothing is copied across.
About PNG
PNG stores pixels losslessly with full alpha transparency. It is ideal for screenshots, logos, UI and anything with sharp edges, but photos saved as PNG are several times larger than JPEG.
A PNG opens with an 8-byte signature and is a chain of chunks, each with its own CRC: IHDR (size, depth, colour type), optional PLTE and tRNS for palettes, one or more IDAT chunks with the compressed rows, and IEND.
PNG files usually come from screenshots, design exports, logos and web graphics.
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 PNG to SGI makes sense
SGI is the better choice for legacy SGI and 3D pipelines, while PNG suits screenshots, logos, graphics and anything that needs transparency.
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
- Blender, GIMP, ImageMagick and Nuke read SGI files, but browsers and most photo apps do not.
More conversions
Related tools
Convert SGI to PNG in your browser, ready for screenshots, logos, graphics and anything that needs transparency. Batch, private, no uploads.
Convert PNG to JPG in your browser, with transparency filled in a colour you pick. Batch, private, no uploads.
Convert PNG to WebP in your browser, ready for images on websites and in apps. Batch, private, no uploads.
Convert PNG to AVIF in your browser, ready for maximum compression on modern websites. Batch, private, no uploads.
Convert PNG to PDF in your browser, one PDF page per image. Batch, private, no uploads.
Convert PNG to ICO in your browser, multi-size icons for favicons and Windows. Batch, private, no uploads.
Convert PNG to SVG in your browser, traced into real vector paths. Batch, private, no uploads.
Convert PNG to EPS in your browser, with transparency filled in a colour you pick. Batch, private, no uploads.
Frequently asked questions
Does converting PNG to SGI lose quality?
SGI is written losslessly, so the pixels are stored exactly as decoded. 16-bit PNGs from photo and scientific software are reduced to 8 bits per channel.
Is transparency kept in the SGI?
Yes. PNG stores it as a full alpha channel, so edges and shadows can fade smoothly, and the SGI is written with an alpha channel, so transparent areas stay transparent.
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.