Increase the DPI is useless ?

[Kelijsto]

Hello.

Increase the DPI in a picture can increase the quality for printing, or it's useless like increase the scale ?

Thanks for your answers.

[JP Hess]

DPI or PPI? DPI (dots per inch) is a printing term referring to what a printer can print. PPI (pixels per inch) is a display term referring to how compressed the image pixels might be. In reality, the only one you can have any control over is PPI. But that really isn't going to have any impact over print quality. The only real value that number has is to give you an idea of how large the image will be at any given PPI setting. It is a calculator setting. Increasing the PPI in an attempt to get a better quality print accomplishes nothing because you still have to exactly the same number of pixels to work with.

[Kelijsto]

Hi JimHess.

I think to dots per inch.

Thanks.

[JP Hess]

What do you mean by that? Image files don't have dots, they have pixels. Printers don't print pixels, they print dots.

[Kelijsto]

The English isn't my natural spiking.

So, let me show you my question with this picture.

[JP Hess · Accepted solution]

I don't know what program you are using to display that image. But the display is not right. You'll notice that it says DPI, but then it reports 72 pixels/inch. And that's really 72 PPI. That terminology is often misunderstood and incorrectly used in many software programs. But basically, changing the DPI (or PPI, it doesn't matter) will have no impact on the quality of an image because the image will still have precisely the same number of pixels no matter what that setting is. If you have your own printer, you can try this experiment. Set the DPI at 72 and print an image at whatever size you want. Then change the DPI to 300 or even 600 and print the same size print again. You will find that there will be no difference in quality whatsoever. The reason is that you are dealing with exactly the same number of pixels. That setting will have no effect on the printer.

[Kelijsto]

Thanks for your help.

Now, I understand what's the best choice.