QuickLook Thumbnail generation problems with Canon CR3 RAW images (Sequoia)

Here is a brief summary of a workaround based on my investigation:

1. create a new folder to receive the CR3 HDR PQ images using Finder Show View Options to disable Show preview icon
2. import the CR3 images into the newly created folder
3. create custom Finder icons for the CR3 images either manually or by using an Automator workflow
4. Use Finder Show View Options to enable Show preview icon

In my case, I was able to view the image icons for both the CR3 HDR PQ files and other image files (see below) without triggering an increase in CPU consumption.

I also heard back from Apple Support who indicated that the problem should likely be fixed in the next Sequoia maintenance update (currently at version 15.2).

- Pie Lover

Below is a screenshot taken with Monterey 12.7.6. Notice that thumbnails for CR3 images are generated as expected. The same images cause a problem with Sequoia 15.2 in that the thumbnail generation process goes into an infinite loop which brings the computer to its knees.

- Pie Lover

I believe that I finally found a workaround for the excessive CPU issue related to thumbnail generation for Canon CR3 HDR PQ files:

Bring up Finder's Show View Options (Finder->View->Show View Options) for the image folder and uncheck the Show icon preview checkbox (see below for the icon view). This should been done individually for each of the icon, list, columns, and gallery views.

With this setup, the ImageThumbnailExtension process is no longer triggered by the presence of CR3 images which avoids excessive CPU consumption during thumbnail generation. This works around a bug which I believe is related to CR3 HDR PQ using an embedded HEIC preview (rather than JPEG).

- Pie Lover

As a last step, I created a custom icon for each CR3 image (using an Automator workflow). The custom icon is displayed as usual (and does not trigger any execution of the ImageThumbnailExtension process).

Although this is an adequate workaround, I'm still hoping that Apple will address the root cause in an upcoming Sequoia update.

- PIe Lover

I never fail to be impressed by how useful the Automator tool can be. As a case in point, it turn outs to be straightforward to turn off Show icon preview:

Here's Finder's Show View Options after running the above Automator action (note that the background colour is changed as I couldn't get the Automator action to retain the default behaviour):

- Pie Lover

Thanks for that suggestion. I just spoke with the Apple Support advisor assigned to my case. He confirmed that the engineering team is aware of an issue with thumbnail generation in Sequoia 15.1 although I couldn't tell whether or not it is the exact issue that I'm experiencing. The advisor mentioned that he is unaware of timeline for a fix but stated that he felt confident that it would be addressed in a "timely manner". I'm afraid that his words weren't that reassuring. :-)

BTW, it seems that CR3 RAW files generated using the HDR PQ option have an HEVC encoded embedded preview rather than the more typical JPEG preview. I suspect that the image thumbnail generation software is not taking this difference into account. If correct, disabling HDR PQ for CR3 RAW should restore the thumbnail function and thus avoid wasting more than half of the Mac mini M2's processing power!

- Pie Lover

I confirmed a workaround for the thumbnail generation issue described in the original post above. You can avoid the problem by turning off the CR3 RAW HDR PQ option in the camera.. Doing so, of course, disables the HDR PQ (High Dynamic Range, Perceptual Quantization) feature.

- Pie Lover

I believe that your statement is not accurate. CR3 HDR PQ worked perfectly well before the update to Sequoia. Also, I've read reports of icons for other previously supported image formats not being generated. Further, Apple support confirmed that the issue that I reported is a known issue.

- Pie Lover

See below for using AppleScript to modify Show preview icon.

- Pie Lover

Turn Off Show icon preview

	tell application "Finder"
		
		open (choose folder)
		
		if (current view of front Finder window) is icon view then
			set (shows icon preview of icon view options of front Finder window) to false
		else if (current view of front Finder window) is list view or (current view of front Finder window) is flow view then
			set (shows icon preview of list view options of front Finder window) to false
		else if (current view of front Finder window) is column view then
			set (shows icon preview of column view options of front Finder window) to false
			if (shows icon preview of column view options of front Finder window) then set (shows icon of column view options of front Finder window) to false
		end if
		
		close front Finder window
		
	end tell

Turn On Show icon preview

	tell application "Finder"
		
		open (choose folder)
		
		if (current view of front Finder window) is icon view then
			set (shows icon preview of icon view options of front Finder window) to true
		else if (current view of front Finder window) is list view or (current view of front Finder window) is flow view then
			set (shows icon preview of list view options of front Finder window) to true
		else if (current view of front Finder window) is column view then
			set (shows icon preview of column view options of front Finder window) to true
			if (shows icon preview of column view options of front Finder window) then set (shows icon of column view options of front Finder window) to true
		end if
		
		close front Finder window
		
	end tell

I've been using the workaround for Canon CR3 HDR PQ files . While the workaround works as intended, I noticed that the ImageThumbnailExtension process is sometimes triggered when I move or delete these files.

The key to preventing the issue seems to be to avoid opening the destination folder in Finder. For example, deleting without opening the Trash Can seems to avoid triggering ImageThumbnailExtension.

- Pie Lover

Digital camera RAW formats supported by iOS 18, iPadOS 18, macOS Sequoia, and visionOS 2 - Apple Support (CA)

Here is an improved Automator workflow for setting or clearing Finder's Show icon preview setting:

Automator script to set/clear Show icon p… - Apple Community

- Pie Lover

The problem as initially described in Sequoia 15.1 persists in Sequoia 15.2.

- Pie Lover