On the Size tab, under Crop from, enter the size numbers that you want in the Left, Right, Top, and Bottom boxes. To reduce the file size of your picture and delete the cropped parts of the picture from the file, under Picture Tools, on the Format tab, in the Adjust group, click Compress Pictures.If you want to keep the cropped parts, you can change the automatic setting.hange the resolution of a picture. Click the picture that you want to change the resolution for. Under Picture Tools, on the Format tab, in the Adjust group, click Compress Pictures. Note If you do not see the Picture Tools and Format tabs, make sure that you selected a picture.