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
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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.
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Set an output directory - I generally use the input directory with a subdirectory "small" to keep things simple.
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Tick the box for "Use advanced options (for bulk resize)" and dive into the options.
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