Photos in the BYO Guitar website can be a maximum of 1500 pixels a side. Easiest way I've found to resize is to use a program such as Irfan View to resize images.
Steps as follows.
Open Irfanview and go to File > Batch Conversion/Rename
Use the file browser to navigate to your photos.
Once you're in the directory you can add all photos or selectively add individual photos if you want.
Set an output directory - I generally use the input directory with a subdirectory "small" to keep things simple.
Tick the box for "Use advanced options (for bulk resize)" and dive into the options.
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