Overview
For example, when delivering images via IIIF, performing the following conversion on CMYK color images using ImageMagick would sometimes result in inverted colors.
Original image
(Using an image published on Nuno LAB..)
Display example in Image Annotator (created by Masahide Kanzaki)
This is not a problem with image servers such as Cantaloupe Image Server or IIPImage, nor with viewers like Image Annotator, Mirador, or Universal Viewer. Rather, the issue lies in the generated tiled TIFF images.
This article describes how to address this problem.
Background
Similar issues have been reported in several places, including the following article.
https://scrapbox.io/giraffate/ImageMagickでCMYKのJPG画像を合成したら色が反転するバグ
As a solution, I referred to the following.
https://www.imagemagick.org/discourse-server/viewtopic.php?t=32585
It appears that adding -colorspace sRGB resolves the issue.
Conversion
The command for creating tiled TIFFs is based on the following reference.
https://samvera.github.io/serverless-iiif/docs/source-images#using-imagemagick
Specifically:
Running the above command as-is on a CMYK color image resulted in the inverted colors shown at the beginning of this article.
Note that I was using Cantaloupe Image Server as the Image Server, but the same issue was also confirmed with IIPImage and others.
Fixed Conversion Command
Add -colorspace sRGB as follows.
As a result, the colors are no longer inverted, and the images display correctly in IIIF-compatible viewers such as Image Annotator.
References
When checking image display, Mirador and Universal Viewer typically require entering a IIIF manifest file URL. However, Image Annotator allows you to enter an image URI directly.
Access the following site:
https://www.kanzaki.com/works/2016/pub/image-annotator
And enter an image URI like the following. Here we are using an image from the Wellcome Collection.
https://iiif.wellcomecollection.org/image/b20432033_B0008608.JP2/info.json
As a result, the image can be displayed as follows.
Summary
I hope this is helpful for delivering images using IIIF.