This question is probably going to sound obvious to alot of you, but I can't decide which method is better. When you crop a photo in Photoshop, do you use the "Crop" feature on the "Tools" section, and crop at 300 ppi, or do you go to Image>crop under the top menu after selecting the part you want to crop? I'm thinking cropping at 300 ppi is better than the alternative?
Using the crop tool set at 300 ppi isn't necessarily better, because that causes PS to resample the image. If the cropped section is initially much less than 300 ppi, you may be upsampling enough to degrade image quality.
Better to crop without entering a resolution value, and then see what resolution the cropped image is. If it's enough for a decent print, you're probably better off to go with that rather than resample.
I do not like to resample an image unless it is really needed. I feel the optically created pixels created by my cameras sensor and lens are of better quality then ones create by interpolating these with some computer algorithm. You can use Photoshop Crop tool and the Marquee selection tool in combination with Image Crop to Crop images without resampling. However if you use the Crop tool and fill in a resolution like 300 dpi. When the Crop is made the crop area will be resampled to 300dpi and you will loose all of the high quality optically created pixels you received from your camera.
IMO resampling is only required in two cases. First reason you need to reduce the number of pixels in an image so it will fit within a web page or e-mail.
Second reason your printing an image that is going to be view close up and the DPI resolution has fallen below 200dpi you need to add pixels to have the image print better.
