I wonder if you can help.
I am still using the Apple Aperture program on my Mac to process my photographs. I am using the latest operating system (macOS High Sierra). I shoot in RAW and as a result all the photos on my mac are around the 25 MB each. However when I transfer the photos to an USB disk to take to be printer, the photos are converted to jpg and the size on the USB disk is reduced to around the 1 MB. The photo printing technician consider this size (1MB) to be a low resolution and cannot get a good print.
Can anyone please tell me how to transfer a high resolution photo from my Mac to a USB disk and maintain the size the same as the one on the Mac?
I appreciate your help.