With Photoshop, how to batch replace white background with transparent in the image
Unfortunately there is no easy quick-fix for this
My typical method of choice is; Go to the channels panel, toggle through the Red Green and Blue options to see which has the most contrast, duplicate this layer and then ctrl/cmd+l the levels slider to increase this. Then using the brush on this layer colour in black what you want and white what you don't. You can then click on this channel for a selection path (ensure you re-click the rgb and uncheck your duplicate channel) and use a layer mask to perform a non-destructive deletion of the area you want to isolate (reverse the selection ctrl/cms + shift + I if necessary).
This site explains it with images too.
There are of course some uglier methods such as the wand too... Depending on the final size of the images, this may be ok. However, for a really high quality cut-out there is no substitute for time.