1. An apparatus comprising: a compression unit configured to compress an image by performing quantization processing using a quantization table and encoding processing on the image, and a determination unit configured to determine whether the image before the compression is color or monochromatic based on a data size of the image after the compression and a mean color difference value of the image before the compression, wherein the determination unit determines the image before the compression is color if the mean color difference value of the image before the compression is equal to or less than a predetermined value and the data size of the image after the compression is equal to or more than a predetermined data amount.