Final answer:
Cropping an image in a document generally results in a decrease in both the image size and potentially the overall document file size. The resolution of the image does not increase simply due to cropping.
Step-by-step explanation:
When you crop an image in a document, part of the image is removed to focus on a certain area, effectively reducing the dimension of the image. As you remove pixels from the image, you are also reducing the amount of data the image holds. Therefore, cropping an image typically results in decreasing the file size of the image itself, and by extension, may also reduce the overall file size of the document, provided the image constitutes a significant portion of the document. Moreover, image resolution or detail per inch does not increase--unless you are cropping a smaller portion and then enlarging it, which can decrease the quality. Therefore, cropping an image usually does not improve its resolution. In most cases, the image resolution stays the same, but detail at the cropped boundaries is lost.
Learn more about Cropping and File Size