“Reading arithmetic coded JPEG files is not implemented”

Question

I am unable to open this JPEG image in Photoshop after I download it.

The error message that I get:

_{Could not complete your request because reading arithmetic coded JPEG files is not implemented.}

However, Google Chrome seems to be able to display the image just fine:

After looking for this online, people suggested changing the extension. I tried changing it to a few different ones, but with no success.

How does one open this file in Photoshop?

Answer 1

There are actually a few formats that Adobe isn't up to date with.. webp is another.

As far as I know if Photoshop won't open the file, it won't open the file. Often it takes some small shareware image app that's more quickly updated and supports a particular new file format to open the image and then resave it into a format Adobe products do understand.

Adobe is a behemoth with the speed of one. It can take years before they implement code to support new formats.

And there's always copy/paste which tends to work from a browser window.

Answer 2

Open jpegcrop (which can read JPEG JFIF images arithmetically coded by IJG jpeglib's jaricom.c).

Click File / Preferences to open the Preferences dialog box.

Ensure "Entropy Coding Method" is not set to Arithmetic, but instead is set to either "Huffman default" or "Huffman optimized". Click OK.

Click File / Save Frame As, then save as a typical Huffman encoded .jpg.

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Besides jpegcrop, any other program built upon the IJG JPEG library (eg, jpegtran) can likely read and/or convert the image -- assuming the library is not excessively old. My primary experience is with the IJG JPEG v8d (circa 2012). Any program/app built on a newer IJG JPEG library than that will very likely work to read/convert images arithmetically encoded by IJG jpeglib's jaricom.c.

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To give you an idea of what standards were used, here's some documentation comments from a circa 2012 version of IJG jpeglib's jaricom.c. At the beginning:

"This file contains probability estimation tables for common use in arithmetic entropy encoding and decoding routines.

This data represents Table D.3 in the JPEG spec (D.2 in the draft), ISO/IEC IS 10918-1 and CCITT Recommendation ITU-T T.81, and Table 24 in the JBIG spec, ISO/IEC IS 11544 and CCITT Recommendation ITU-T T.82."

then at the end:

"This last entry is used for fixed probability estimate of 0.5 as suggested in Section 10.3 Table 5 of ITU-T Rec. T.851."

Answer 3

• Open the file in Google Chrome.
• Then Control click the image and copy the image.
• Open Photoshop and create a new page from the clipboard and set the resolution you need along with the colour mode.
• Paste the image and save the file to what ever format you need.
• Done