I have done similar work for a company called KCS in the United Kingdom, involving image editing for their catalogue and website. There is a script you can run in photo shop called an 'Image Processor'. It will select all of your images and convert them from png to jpeg, shrink them down in file size, and will still keep their dimensions. I tested your PNG file and converted it to JPEG, the lowest it can go without affecting file quality is roughly 77kb, image sizes will vary depending on the image.