Our local Rotary Club has its own camera club, and I put galleries of images on to the Rotary Website from time to time.
This month I found that the Export function was hanging after a lot of disc activity, and checking the Exports folder I found that one of the images hadn't been converted into the corresponding lower-resolution image and thumbnail.
This image was a large .jpg file - 12 MBytes - and my first thought was that the file was too long for a buffer. I therefore opened it using Photoshop, and saved at a lower quality, to reduce the file-size below those of the others (which had been converted satisfactorily). This didn't work, and after some further experiment I found that the image resolution was 3944x2972 pixels, and that halving these dimensions solved my problem.
If there is a maximum number of pixels that Gallery Mage can manage, perhaps this should be checked and an appropriate error message issued when an overlarge file is being processed.
Thanks for a great product - just hoping to make it even better...