What processes do you use to keep them up to date?
Do you have a scheme for tracking screenshots to builds?
How do you handle pre-release screenshots?
For pre-release screenshots: crude photo editing or preferably a ui wireframe tool.
For marketing: a demo login would be great, and for the few places that you demand a screenshot just take it manually with a user and content created specifically for that purpose.
For keeping up to date: if you must, have an automated job (much like CI UI test job) to take and upload screenshots whey you deploy to production.
For finding versions: have your SAAS show the version in a corner, always. I prefer a ISO8601 timestamp of the frontend build.
Tracking screenshots to builds has been an outcome of feature releases that included documentation w/screenshots. The documentation was part of the feature epic, and the epic was associated with a product release. The product releases had a product version.
What processes do you use to keep them up to date?
Feature updates include a documentation review, docs include screenshots. Depending on your org, some ownership between documentation teams or the feature owner can call out if an update is needed. For documentation teams to be enabled to make this call out, they should be provided with a feature outline that includes relevant screenshots. Relevant screenshots show product differences between empty state and the feature in use. It can be helpful internally to use a tool similar to Sketch to indicate the points of interest regarding empty state versus feature action.
It can also be helpful to have feature onboarding capabilities in your UI, something that guides customers through the feature with live data. Onboarding via the UI in my experience is a one-time event.
For documentation teams: Tie your docs (containing the screenshots), directly to the feature epic (or whatever you use) that will be released.
For marketing teams: I've worked with teams that used the same or similar source material as the documentation teams. The marketing teams can simply reference the product version somewhere in the marketing material. This calls out that the docs are dated, rather than attempting to update them. Preference is for new marketing material with updated screenshots, versus updating older marketing material.
How do you handle pre-release screenshots?
I'm assuming that pre-release may be synonymous with beta release.
You may be able to provide access to pre-release docs (including screenshots) via your normal docs UI if your docs are behind your feature gating systems. This can leverage the same docs > epics > release association. My greatest obstacle has been the docs not being complete for pre-release, not the portal itself. Instead, I've delivered PDFs or a similar format of documentation w/screenshots to beta customers in the upmarket > enterprise space. That has worked well, since there is frequently a manual onboarding associated with beta customers and innovative features in that space. I could see that not being the case in b2c or other scenarios.
Personal processes
I make feature screenshots and drop them into Joplin, annotating them at the time, so I remember why the screenshot was made. e.g., did something look wrong, was there something I should call out, did we fix a bug that provided different data? This also preserves a personal history so that I don't have to remember and provides a checklist of what I need to update. The web clipper function is helpful for getting historical doc references as well.
My experience is primarily in startups working with b2b upmarket > enterprise SaaS, so please keep that context in mind.