The K25 file (.k25)

K25 is the picture format of a single camera, the Kodak DC25. Kodak announced it on 17 September 1996, in time for Photokina, at US$595. It had a 1/3-inch CCD, 2 MB of internal memory and a slot for CompactFlash cards, which made it one of the first digital cameras to use them. Pictures were 493 × 373 pixels at the high-resolution setting.

A K25 file isn't a JPEG with an unusual name. It holds the sensor's raw readings, one 8-bit value per photosite, plus a tiny ready-made thumbnail. Software on a computer had to turn the raw data into a picture. That makes K25 a very early camera raw format, long before the word was common.

Kodak's DC25 software is decades old and Kodak has left the camera business. The route that works today is LibRaw, the open-source raw decoder, which lists the DC20 and DC25 among its supported cameras; dcraw, the program LibRaw grew from, handles them too. In Python, the rawpy package wraps LibRaw:

# pip install rawpy imageio
import rawpy, imageio.v3 as iio

with rawpy.imread("DC0001H.K25") as raw:
    print(raw.sizes)  # raw and output dimensions
    rgb = raw.postprocess()
iio.imwrite("DC0001H.png", rgb)

LibRaw recognises the camera from the file's contents, so the extension doesn't matter. Mainstream photo apps, Apple Photos and browsers don't open K25 files. Expect a soft, small picture: that's the camera, not the conversion.

• The program has never supported it. Almost no image viewer does. Use a LibRaw- or dcraw-based tool.
• It opens as a broken TIFF. Some tools see the MM header and try to read a TIFF. The content isn't one; use LibRaw.
• The file is the wrong size. A high-resolution K25 should be 140,352 bytes. A file that's much shorter may have been cut off when it was copied from an old card or disk.
• Colours are odd. Modern decoders only approximate Kodak's processing of 1996. Adjust white balance by hand after converting.

If you've found DC25 pictures on an old disk or card, keep the K25 files unchanged and convert copies to PNG, which is lossless and opens everywhere, or to 16-bit TIFF if you plan to edit. The Library of Congress warns that proprietary raw formats risk losing software support in the long term, and K25, with one camera and one maintained decoder, is an extreme case.

For the other Kodak formats, see KDC and the professional DCR.

According to the reverse-engineered description, a K25 file stores a picture name and a date. There's no location: the DC25 had no GPS. K25 files contain no scripts or macros.