Workflow to find original images in library

This is a partial answer. I will add to it as I work out the details.

Exiftool (https://exiftool.org/) can be used to extract lots of interesting metadata tidbits from images.

Starting at my image directory:

exiftool -r -ImageSize -Model -DateTimeOriginal -ImageNumber .
======== ./Seedlings/Spruce_2+2_1.jpg
Image Size                      : 299x400
Camera Model Name               : iPhone 4
Date Created                    : 2015:05:17
======== ./Seedlings/Spruce_2+2_2.jpg
Image Size                      : 267x400
Date Created                    : 2015:04:29 12:58:16

Note that all data isn't present for all images. One of the apps on my phone, "Night Camera" puts very little metadata in the image. Note also that sometimes I just get a date and not a full date/time. Turns out there are 12 time stamps. I changed the command above to -DateTimeOriginal as it seems to be best supported.

If it seems that I'm a bit nuts about dates, there's method to my madness: When I import images, they get renamed yyyy-mm-dd_hh:mm:ss so with some changing of : to - and space to _ I can get the actual original filename.

The -r in the example command will go down my image tree recursively. Save this to a file.

Step 2

Check it to see that every file has a meaningful date. I may decide to pull further info.

This is also my time to rationalize my folder structure. Over the 10 years I've had my web page, 'things jest grew'

My thinking right now is that I will export a version of each image as a 3000 x 2000 pixel jpeg. That's too large for now, but hey, Bill Gates said no one would need more that 640K ram in a PC.

Using ImageMagic I will then create a set of images from each large image reducing pixel dimensions by a factor of 1.414 (square root of 2) with a sharpening stage between. See http://www.controlledvocabulary.com/imagedatabases/downsampling.html for details about this.

ImageMagic is a suite of command line tools for image manipulation. The syntax is extensive, somewhat arcane, and it's generally not a tool for use on a single image. But if you need to work on a thousand or so images it saves a lot of time.

The same script I write to use ImageMagic will also write srcset snippets.

Right now, I write my webpages in Markdown, so an image looks like this:

<DIV class="picr">

![Typical Pine](/Images/Shelterbelt/Shelterbelt-3.jpg)

Caption goes here

</div>

This will get replaced with

<DIV class="picr">

[% INCLUDE srcset/Shelterbelt-3.sst]

Caption goes here

</div>

All that is manual work, but because the srcset file tree is separate, there will be continuity as I change each image. If a user has the older cached image, he's no worse off than before.

Intent is to go after the pages most frequently used by mobile first.

Partial answer as well, but perhaps helpful.

Now

I understand your current issue as: you have multiple downscaled versions of an image, but cannot find the original image anymore.

Software that can look for visual duplicates of photos might be a solution. This previous question has more information on that.

Future

Manual

For the future, if you want to stick to the manual process of creating different sized versions of an image you should be able to tackle this problem:

My photo manager doesn't track exported files.

If you use something like Lightroom as your photo manager, you can export various sizes and keep the original filename in the exported image.

E.g.: you have a photo called "IMG_1234.jpeg", you can then export a 256px, 512px and 1920px wide versions and automatically call them:

• IMG_1234-256.jpeg
• IMG_1234-512.jpeg
• IMG_1234-1920.jpeg

Command line applications like ImageMagick can do something similar.

Automatic

You mention that you use Markdown to create your website, so I assume you are using a static site generator. In that case you should be able to find a plugin which can handle generating images of different sizes automatically (i.e. responsive images).
This article explains a complete setup. Perhaps it's too much for your goal, but you could draw inspiration from it.