PNG to RAS Converter
Convert PNG to RAS in your browser. PNG files usually come from screenshots, design exports, logos and web graphics; RAS is the better fit for legacy Sun and Unix software. You get a 24-bit run-length encoded Sun Raster image. 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 RAS
- 1
Add your PNG files: drop them here, choose them, or paste from the clipboard.
- 2
Pick the colour that replaces transparent areas, since RAS has none.
- 3
Click Convert. Each file is decoded and encoded in a background thread on this device.
- 4
Download the .ras files one at a time or together as a ZIP.
Why use Aback Images for png to ras
Where the RAS goes next
RAS opens in ImageMagick, GIMP, XnView, IrfanView and Netpbm.
RAS next to PNG
Both sides are lossless, so the size depends on how well the RAS encoder handles this picture compared with the PNG's lossless DEFLATE with a prediction filter chosen per row.
Written without a lossy pass
The RAS 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 RAS
What changes from PNG to RAS
Encoding: the PNG uses lossless DEFLATE with a prediction filter chosen per row; RAS uses none or a byte-oriented run-length encoding (RT_BYTE_ENCODED), and the download is a 24-bit run-length encoded Sun Raster image.
Bit depth: 1, 2, 4, 8 or 16 bits per channel in the PNG; RAS allows 1, 8, 24 or 32 bits per pixel, and the RAS written here has 24 bits per pixel. 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; RAS supports monochrome, a colour map, or RGB stored as BGR, written here as 8-bit sRGB.
Transparency: the PNG stores it as a full alpha channel, so edges and shadows can fade smoothly; the RAS has none, so transparent areas are filled with the colour you choose.
Metadata: the PNG can carry text chunks, an ICC profile, physical resolution and EXIF in an eXIf chunk; RAS can carry only a 32-byte header with size, depth, type and colour map length, 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 RAS
Sun Raster is the bitmap format of Sun Microsystems' SunOS and Solaris workstations. It stores 1, 8, 24 or 32-bit pixels, optionally with a colour map and simple run-length compression.
A Sun Raster file starts with the magic number 59 A6 6A 95 and a 32-byte header (width, height, depth, data length, type, colour map type and length), then the colour map and the rows, each padded to an even number of bytes.
When converting PNG to RAS makes sense
RAS is the better choice for legacy Sun and Unix software, while PNG suits screenshots, logos, graphics and anything that needs transparency.
RAS strengths: Simple and well documented; Read by ImageMagick, GIMP and many viewers. Drawbacks to weigh: Obsolete outside old Unix systems; No transparency in practice; Weak compression.
Limitations
- Sun Raster has no alpha channel, so transparency is flattened onto the background colour.
- Modern viewers such as IrfanView, XnView and GIMP still open it.
More conversions
Related tools
Convert RAS 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 RAS lose quality?
RAS 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.
What happens to transparency when converting PNG to RAS?
PNG stores transparency as a full alpha channel, so edges and shadows can fade smoothly. RAS has no alpha channel, so transparent pixels are composited onto a solid colour, white unless you pick another. To keep transparency, convert to PNG, WebP or AVIF instead.
Which apps open RAS files?
ImageMagick, GIMP, XnView, IrfanView and Netpbm. 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.