RAS to JPG Converter

You found a .ras file in an old project folder, a unix archive or a scientific data set, and nothing on your computer will show it. RAS is the Sun raster format. This page decodes it directly in your browser and saves an ordinary JPG, so you can look at the image, share it or print it.

Drop images here, click to choose, or paste with Ctrl+V
RAS files · many files at once · nothing is uploaded
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Free to use on any site. Paste the code where you want the tool to appear. It runs inside the page; visitors' files are processed in their own browser and are not uploaded.

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WordPress and most site builders have a "Custom HTML" block where this code can be pasted. The embed keeps a small link back to CalcMaster.

How to convert RAS to JPG

  1. Add your RAS files by dropping them, clicking the drop zone or pasting.
  2. The output format is already set to JPG. Adjust quality or size if you need to.
  3. Press Convert and compare the original and new size for each file.
  4. Download each file or all of them as a ZIP.

When to convert, and when not to

  • You inherited an archive from older unix workstations and want to view the pictures.
  • A website, office program or phone refuses a .ras attachment.
  • You want one common format for a mixed folder of legacy graphics before handing it to someone else.
  • Do not convert a 1-bit scan you may need to process further. Keep the original RAS, or choose PNG, because JPG adds grey noise around hard black and white edges.

What changes

  • The tool reads 1-bit, 8-bit, 24-bit and 32-bit Sun raster files, including the run-length encoded variety.
  • Pictures that use a colour map are expanded to full colour using that map.
  • Raster files that wrap TIFF or IFF data are not supported and produce a clear error.
  • JPG is lossy and has no transparency, so any see-through part takes your chosen background colour.
  • Anything stored in the file's header besides the pixel data is not written to the JPG.

Where Sun raster files come from

The Sun raster format was written by programs that ran on Sun workstations, and it turns up in screen captures, scientific output and image libraries from that world. A file is simply a short header followed by pixel data, sometimes compressed, sometimes accompanied by a table of colours.

Because it was never adopted by mainstream photo software, current viewers do not recognise it. Converting is therefore the easiest route from a niche format to something every device understands.

What the tool does with each kind of RAS

A 24-bit or 32-bit file already holds colour for each pixel, so the tool reads the values and saves them. An 8-bit file usually carries a colour map: each stored number is looked up in that table to get its real colour. A 1-bit file is plain black and white.

Files in the run-length encoded variety are expanded first, which gives the same pixels as the uncompressed type. You do not need to know which one you have. If the file turns out to be one of the unsupported kinds, you see a message saying so rather than a corrupted result.

Keeping 1-bit images crisp

Black and white images are a special case. A JPG made from a 1-bit raster can show faint grey halos near edges, which matters if you are going to read small text in the picture or run it through other software. Switching the output to PNG keeps the edges clean, at the cost of a larger file for photographic content but not for simple black and white scans.

If you do stay with JPG for a 1-bit file, set the quality slider high and view the result at full size before converting a long list.

Checking the result

After converting, compare the JPG with how the picture looked in the program that made it, if you still have one. Colour-mapped files are the most likely to show a difference, because a wrong map would change every colour at once. If the picture looks right, run the whole batch. If a result looks odd, convert that single file with PNG as the output to rule out compression as the cause.

Privacy: your files stay on your device

  • The tool decodes, resizes and encodes your pictures with your browser. The files are never sent to a server.
  • To check it yourself: open the browser developer tools (F12), open the Network tab, convert a file, and look for any request that carries your image. You will see none.

Frequently asked questions

What is a .ras file?

It is a raster image saved in the Sun raster format, common in older unix and scientific work. Most current photo viewers cannot open it.

Does the tool support colour-mapped RAS files?

Yes. The colour map in the file is used to restore the real colours before the JPG is written.

Why did I get an error for my RAS file?

A few variants, such as ones that embed TIFF or IFF data, are not supported. The message tells you when that is the reason.

Can I get a lossless result instead?

Yes. Change the output format to PNG in the options panel. It keeps every pixel exactly as read.

Do my files leave my computer?

No. Everything happens in your browser, and no file is uploaded.

Can I convert several RAS files at the same time?

Add them together, press Convert, and download them one by one or as a ZIP.

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