StarTools

I have been saving all my work as PNG files and learned today when I went to a photography print shoo that the DPI is way too low. I am not able to see what this number is anywhere, but the guy at the shop said it was at 90DPI.

How do I save an image from ST with DPI of at least 300? Also, after an image is saved, how do you find the DPI of that image?! have been unsuccessful in finding this in the manual I downloaded or a search of the forum.

Thanks in advance.

Aaron

G'day Aaron

Shame the print shop guy didn't give you a bit more information.

Every digital image has a pixel dimension i.e. 1920 x 1080, 320 x 240 etc...

The 'resolution' bit comes in when that is translated to a physical dimension - i.e. inches.

So - for example, if you had an image with a pixel size of 1920 x 1080 and wanted to print it at 150 dots-per-inch (DPI), then the biggest you could manage would be 12.8" (1920/150) x 7.2" (1080/150).

My DSLR produces native images at 5184 x 3456 pixels. In StarTools, I bin by 50%, which gives me a maximum image size (before cropping) of 2592 x 1728 pixels. If I wanted to produce a 10" x 8" print from that, the highest dot density I could achieve would be about 216 DPI (1728/8").

Some graphics programs have a 'canvas size' provision which relates to the notion of physical print size.

Does that help some?

Nev B.

That does help, thank you. I will use your formula for future calculations.

Is it you opinion/experience that 300 DPI is a minimum for good quality printing or is it dependent on what you are printing on? I have done quite a bit of research but have not found much info on image quality requirements for professional printing.

Thanks again for your insight.

Aaron

Yes, it does depend on the printing process, but around 300 dpi is a good target and should give you good results in most processes.

My inkjet printer has a native resolution of 360 dpi if I recall correctly - so I target that for images that I want to be as good as they can be.

You could probably get away with as low as 150 dpi for large prints, but they are going to look a little ordinary if you get up close.

Check with your printing provider if using an external service - they should be able to give you some indication of the ideal parameters for good results.

And there's always the colour space on top of all this...... but let's not go there.... It's a mind bender (for me anyway)!

Cheers

N