Cropping in CS5 reduces sharpness

KongKurs · Jan 22, 2011

Whenever I'm cropping in CS5 it asks for the DPI.
This is resulting in my large original TIFF and JPEG photos from my camera being drastically reduced in size, e.g. an original photo being reduced from 6 MB to 1 MB or less! I'm using 300DPI which should be pretty much a standard, right?

Is there any way of cropping without changing the resolution of the picture this way?

In my old Photoshop Elements this was easy, but not in CS5?

KongKurs · Jan 22, 2011

I've just tested by cropping almost nothing off a picture...

The original is 4272 x 2840 pixels and the size is 5,16 MB. Properties says the photo is 300dpi.
Then I cropped as little as I possibly could, and one should presume the dimensions of the photo would be about 99% of the original, but no...
The cropped is now 1800x1200 and the size is 1,21 MB. Also 300dpi..

Why? And how to maintain original resolution, when the original actually is 300dpi

Peano · Jan 22, 2011

KongKurs said:
Whenever I'm cropping in CS5 it asks for the DPI.

Where does it ask for dpi?

Before you crop, is the Resolution window blank, as shown here?

Opher · Jan 22, 2011

Leave the resolution box blank and ti will not resize.

KmH · Jan 22, 2011

KongKurs said:
I've just tested by cropping almost nothing off a picture...

The original is 4272 x 2840 pixels and the size is 5,16 MB. Properties says the photo is 300dpi.
Then I cropped as little as I possibly could, and one should presume the dimensions of the photo would be about 99% of the original, but no...
The cropped is now 1800x1200 and the size is 1,21 MB. Also 300dpi..

Why? And how to maintain original resolution, when the original actually is 300dpi

The original has no ppi or dpi. It only has pixel dimensions.

Digital images don't have dots - dots per inch (dpi). Ppi and dpi are not interchangeable terms.

PPI is meaningless until an image is printed.

MB is the file size.....Not the image size. Changing the ppi would have no effect on image file size, but the crop does. You went from a 12.2 MP (megapixel, not mega byte)(4272x2840=12.2MP) photo to a 2.16 MP image (1800x1200=2.16MP). You discarded 10 MP, which also reduces the image file size.

Image size is the pixel dimensions divided by the ppi.

SlickSalmon · Jan 22, 2011

KmH is normally correct about everything, but in this case I'd refine his answer. Photoshop thinks about resolution in terms of in pixels/inch. If you leave that unchanged when you crop, then your resolution will remain unchanged. If you change the pixels/inch, then the program uses a resampling algorithm that adversely affects the crispness of the image.

So, if you leave the "pixels/inch" box blank when you crop, the program will trim off pixels from the area outside the crop and will not resample the image. The resolution will remain the same as the original image. The file size will get smaller by the number of pixels that got chopped off.