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Enhancing Indistinct Postmarks

On June 13, 2023, 7:53 pm Bas PAYNE wrote in the in the "Working with Postmarks" thread "We really need a better software tool to achieve a better result more quickly and more automatically." Help may now be at hand.

As a direct result of Bas' comment, I have been contacted by SAPC member Clive Levinson, an ex-South African living in Canada, who has written a software progam called ImageSleuth. It is FREE and downloadable from his website. (Link below).

ImageSleuth facilitates the discovery of hidden content in documents and images. It offers postal historians a way to enhance postmarks on stamps in order to see them more clearly. By separating a source image, the stamp bearing an indistinct postmark, into its component colourspaces various transformations can be applied to the colour-separated image to reveal hidden detail barely visible to the naked eye.

Once it has been downloaded and installed, ImageSleuth can remain on the user's PC indefinitely without relying on a link to a third-party website. To give us some idea of what ImageSleuth does, Clive downloaded the image from the first "Working with Postmarks" thread. Here it is Before (left) and After being processed with ImageSleuth (right).

It certainly makes this particular postmark more distinct to the naked eye.

Clive previously used the University of Utah's website to quickly and easily identify postmarks by highlighting them.  The University of Utah's retroReveal website went offline in May 2022 and is unlikely to return. Using retroReveal's algorithms that had been made public Clive created ImageSleuth, a software tool with all of retroReveal's functionality plus some added enhancements of his own.

ImageSleuth is intended as a free, cross-platform, standalone replacement for retroReveal. Recently a new website has appeared. This is not the same as the original University of Utah's website but has been created by someone using an older version of the retroReveal code with less functionality. Clive's new ImageSleuth Version 1.2.0, released in April 2023 provides the same high level of improved "forensic-style image processing" while adding new features for FREE.

ImageSleuth is available for Windows, Mac or Linux and does not require an Internet connection in order to function.

ImageSleuth may be downloaded from:

This is a good start. Clive is the author of AlbumEasy, free page layout software for creating DIY stamp album pages. Since first releasing it in 2005, Clive has now issued 24 updates to AlbumEasy. As a result, anyone downloading and using ImageSleuth can reasonably hope to see further product development in future. Indeed, Clive already has some ideas for further enhancements which will increase the usefulness of ImageSleuth for postmark researchers. He hopes to add these in the near future. No doubt, a number of SAPC members would like to submit a Feature Wish List. Anyone downloading and using this program can give their feedback to Clive directly via the Contact Form on his website.

Jamie Smith has reacted to this post.
Jamie Smith

I have used ImageSleuth and  found is simple, quick and straightforward. I attempted to find the postmark in five images of varying quality. I got a useful result from two, a 40% success rate. It seems to me that at present it works better with images that have a legible postmark rather than with the ones that don't, which are typically the ones we need help with. Nevertheless, some will find it useful in its current form but many others who expect blood from stones - magic - or postmarks from images with no detail will not.

I have written a review of ImageSleuth which its developer describes as "excellent" despite me being honest in my appraisal of the program's capabilities at present, especially that which it does not do as well as I would like. I have decided not to post the review because a new version will be released shortly which will, I hope, address some of my concerns and observations. At the very least, it is encouraging to know that ImageSleuth is in development with the aim of improved postmark recognition. That is good news for postal historians. I will review the new version once it is released. There is no point making points now about issues that will soon be improved.