Why do you want the ppi of the photo to be 300 ppi? PPI determines the physical size of a photo (a print).Ī photo that has pixel dimensions of 3888x2592 pixels that is assigned 300 ppi will print - 3888 pixels ÷ 300 ppi = 12.96 inches by 2592 pixels ÷ 300 ppi = 8.64 inches. Resampeling to a higher resolution means new pixels have to be made up that were not actually recorded by the image sensor. If Resample is not checked, the pixel dimensions will be grayed out and any changes you make will only not affect them. With Resample checked, when you alter one set of units all the others adjust at the same time. The Image size dialog box normally opens with the Resample box checked. DPI is an output device resolution, like an inkjet printer. PPI is an input devices resolution, like digital cameras. If you do the math the difference between 16200 pixel, 3888 pixels, and 72 ppi, 300 ppi is 4.16666.Ī close look shows that Photoshop is careful to use the correct term - ppi, or pixels per inch. The numbers you saw '16200x10800!' are the result of the difference between 72 ppi and 300 ppi. If you make the image smaller, then you want bicubic sharper.Ī very handy book for Photoshop user's to have on the shelf near their computer for reference is - Adobe Photoshop CS5 for Photographers: A professional image editor's guide to the creative use of Photoshop for the Macintosh and PC If you add pixels (make the image larger) then you want bicubic smoother. This will allow you to change the PPI without it automatically changing the pixels.Īs far as which resample option to choose.that is for when you actually do change the number of pixels. To do this, without changing the size of your image (in pixels), you go to the Image Size dialog, but before you change anything, un-check the 're-sample' box. So in that case, you probably do want to change the PPI to something like 300. The confusing part is that sometimes, when you go to print etc., the printer will take the size in inches (on screen at 100% zoom) as the print size.

The important part is how many pixels it has.3888x2592. You could have an image that is 3888x2592 at 72 PPI and it will be exactly the same quality as a file that is 3888x2592 at 600 PPI. It just tells a computer how larger to display the image. In terms of quality, the PPI number is mostly meaningless.

What you are talking about it PPI (pixels per inch).

Photoshop 72 dpi how to change