100% crop means you crop a small section of a photo/picture which is viewed at 100% its resolution.
for example, you've got a 10MP photo, the dimensions are lets say 3888 x 2592 pixels.
if you want to link the image directly on the forums for ppl to view it at 100%, it would be far too huge to view it on an monitor, so what they do is that they crop a section off this 3888 x 2592, maybe a 500x500 area. that would be smaller.
purpose of this?
- to view the image quality at pixel level (100% zoom)
- to zoom in on a certain (small) detail in the image
instead of using the whole 10MP photo, for eg.
how to do it?
just use the crop tool in photoshop (or equiv image editing software) and crop a small section off your image. that's it. don't resize. and make sure ur image hosting website doesnt resize it too.
Ok, when you open your photo in Photoshop(or any other PP program), zoom ur pic to 100% (which usually means you will not be able to see the entire shot, only a portion of it), then using the rectangle selection tool, select an area, then crop away every thing other than the selection.
The resulting image is a 100% crop. Because 1) it is at 100% zoom, and 2) it is a cropped portion of a larger shot.
The primary purpose is to show sharpness (or lack of sharpness), or to draw attention to a certain area of a shot.