One, set the resolution of the size of the resolution, the larger the resolution of the more data of course, the larger the file

Two, set the size of the precision, the more detailed the image, the lower the compression rate, of course, the larger the file

Three, the photo of the color of the complexity of the image if the complexity of the file, the data can be compressed space will be smaller, the file will be larger. The space of the file will be small, of course, the file will also be larger. This difference you can look at the same resolution, the same precision settings to take different photos, to see if the image size is exactly the same. If you use TIFF or RAW format, this difference does not exist, because these formats are not compressed.