Canon's HEIF Implementation
This is a thread to discuss how Canon has utilized the HEIF image file format for their recent cameras.
Other manufacturers also have products with HEIF files, but please keep this thread focused on Canon cameras.
(Feel free to start your own thread to discuss other HEIF related camera manufacturers.)
What is the HEIF, aka High Efficiency Image File Format, file specification as a standard? From the US, https://www.loc.gov/preservation/digital/formats/fdd/fdd000525.shtml, which includes excerpts from: https://github.com/nokiatech/heif
"... an international standard defined by MPEG-H Part 12 (ISO/IEC 23008-12)"
"HEIF has the following basic design:
Still images are stored as items. Typically image items are independently coded, and do not depend on any other item in their decoding. If predictively coded image items with coding dependencies are present, this is clearly signaled. Any number of image items can be included in the same file.
Image sequences are stored as tracks. An image sequence track can be indicated to be displayed either as a timed sequence or in a non-timed manner, such as a gallery of images. An image sequence track may be used instead of image items when there is coding dependency between images.""
... Additionally:
"HEIF is a media container format. It is not an image or video encoder per se. Hence, the quality of the visual media depends highly on the proper usage of encoders. The initial standard supports image bitstreams encoded in HEVC (including its SHVC and MV-HEVC extensions), AVC, or JPEG. This can be extended to support future encodings. HEIF has features not present in other image file formats. Some of these features are":
"Encapsulation of images coded using HEVC, SHVC, MV_HEVC, AVC, and JPEG"
"Encapsulation of image sequences coded using HEVC, SHVC, MV-HEVC, and AVC"
"Support for computational photography use cases"
"Support for both lossy and lossless image data storage"
"A way to distribute still images, image collections and related metadata."
In summary, HEIF files ARE NOT image files! HEIF files are container files, which can contain images structures as specified from each manufacturer.
(The following references: https://en.canon-cna.com/pro/infobank/image-file-types/#:~:text=As%20in%20a%20JPEG%2C%20the,%2C%20which%20are%208-bit.)
For this discussion, Canon HEIF containers are implemented with contents that are Canon defined and Canon specific. I believe that all Canon cameras with a Digic-X processor can create HEIF files with similar properties.
"As in a JPEG, the effects of camera settings such as white balance and Picture Style are "baked in", but Canon HEIF files are 10-bit, meaning they contain four times more colour and tonal information than JPEGs, which are 8-bit."
"Despite containing four times the colour data, HEIF files are typically about the same size as JPEGs, because HEIF compression is 50% more effective than JPEG (hence the "high efficiency" part of their name). The compression algorithms are also more modern than those used in JPEGs, which should prevent the artifacts and colour banding common in highly-compressed JPEGs."
Additionally, the Canon HEIF variant allows use of HDR-PQ ((Perceptual Quantizer), not a big deal IMO and at the moment.
Comments
With the above out of the way, how is Canon HEIF to use? My particular Canon HEIF capable camera is the EOS R7, APS-C Mirrorless body.
My camera shipped with an older firmware, so the first task was to download the latest file from Canon and install it. I am now at version 1.3.1
I also needed the latest Canon DPP-4. I understand from others that Canon has made improvements to DPP which affect HEIF, so make sure you are current.
Went to a local park searching for possible HDR views. This day was bright sunshine with distant white, fluffy clouds, but the scene also included some trees, and the trees still had their leaves so some deep shadows. I shot simultaneous RAW plus HEIF.
Back at home, I chose one frame from the set of this scene, and processed the HEIF files first. DPP really is good for working on these files and gave me several options for output file formats too. I chose both JPG and TIF 16 bit to output.
Next I processed the CR3 RAW files, with the same output file types of JPG and TIF 16 bit. I kept the HEIF sourced output files separate from the RAW sourced output files.
Now I loaded the TIF files into RawTherapee for some post-processing. I found the HEIF 10-bit files nicely malleable with regard to all sorts of moderate processing, and much better than trying to use JPG files. The claims of 4 times as much color and luminance data for 10-bit HEIF sourced files vs 8-bit JPG sourced files seem to be true.
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HEIF into DPP out as TIF-16 into RawTherapee and out as JPG file.
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HEIF on the left, RAW on the right
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HEIF into DPP out as TIF-16 into FastStone relight shadows and out as JPG file. Notice additional details emerge from tree shadows.
You may need to open this image in a new browser tab to see the additional shadow detail.
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Bottom line, I'm a believer. Canon 10-bit HEIF files do contain much more post-processing opportunities. Instead of shooting to RAW plus JPG for some redundancy, I'm staying with RAW-CR3 and 10-bit HEIF which allow much faster turn-around in post-processing, plus more post-processing malleability too.
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