How properly prepare raw-files for big format printing?

Started 3 months ago | Questions thread
David1961 Senior Member • Posts: 4,984
Re: How properly prepare raw-files for big format printing?

The first thing you need to realise is that dpi and ppi are two totally different things.

My Epson printer has a native print resolution of either 360ppi or 720ppi, depending on print quality I set, but prints at 5760dpi.

Canon, HP and most other inkjet printers have a native print resolution of 300ppi.

PPI, not DPI, is set to size an image for printing.

To help you size your image for the paper size you want to print to, this is an example of what happens under the bonnet/hood when you submit a print to an inkjet printer.

For the sake of simplicity, let's say my camera outputs a 3000px x 1500px image.

Now, lets say I want a 12in x 6in print.

Lets say I choose 360ppi print quality on my printer - one of my printer's two native print resolutions - 360ppi or 720ppi.

In the printing app I set the resolution to 250ppi to give me a 12in x 6in print for the 3000px x 1500px image.

In this case the printer reports back to the print application that it wants an image at 360ppi since I chose 360ppi print quality.

So, for a 12in x 6in print it wants an image with size 4320px x 2160px --- (12x360)px x (6x360)px.

But the printing app sends the printer an image with only 3000px x 1500px.

The printer then scratches its head and says "Oops, I haven't got enough pixels in that file for a 12in x 6in print".

After submitting the print job in the print app and before the printer starts outputting the print, somewhere in the print pipeline the 3000px x 1500px image is resampled to 4320px x 2160px.

The printer then prints out onto paper the 4320px x 2160px resampled image.

The main argument you will see in forums like this is whether it is better to let the print pipeline resample images to the printer's native printer resolution or whether the user can do a better job resampling the image to the printer's native printer resolution prior to submitting the print.

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