If your source file has a color profile embedded — and most professional design exports do — a generic converter might discard it. The result looks fine on your screen but prints with shifted colors. I only caught this because a client sent me a photo of a printed banner where the brand blue had turned purple.
Now I make sure the converter preserves embedded ICC profiles, and I check the output against libwebp 1.4.0 encoder documentation expectations for color handling. It is one of those things you do not think about until it burns you. Then you never forget.
The same applies to metadata. Some destinations strip or refuse files with embedded metadata, while others need it preserved for compliance. Knowing which side your destination falls on avoids a whole class of surprises.
I used to convert files one at a time, checking each output manually. That worked for ten files. It did not work for two hundred. After one painful project where I had to redo thirty files because I missed a transparency setting, I built a routine that has not failed me since.
The key is doing three things in order: validate the source format against the WebP Container Specification, pick the right output settings for the destination, then spot-check the first three outputs before batch-processing the rest. photo converter handles the second step automatically — it detects what the destination needs and applies the right settings without me having to remember every format quirk.
The order matters more than people think. Validating the source before converting catches malformed inputs early, so I stop wasting time on files that were never going to convert cleanly. That single reordering cut my error rate by more than half.
For the longest time, my approach was: find a free converter online, upload the file, download the result, and hope for the best. It worked maybe 80% of the time. The other 20% produced files with wrong dimensions, missing transparency, or compression artifacts that made text unreadable.
The real problem was not the converters themselves. I was not checking the source file against Google's WebP compression study before converting, so I was feeding malformed inputs into tools that silently produced broken outputs. No error message, just a bad file.
I finally stopped when a client's logo shipped with a corrupted alpha channel and they caught it on a large-format print. That reprint cost more than any converter subscription would have. Now I validate the source first, every time.
At the end of the day, the goal is an output you do not have to worry about. If a single step here saves you one redo, it was worth the read. I keep the WebP Container Specification bookmarked for the days I doubt myself, and I run my checks on every export before it ships.