I just discovered digital prints on etsy about a month ago and I've been scrambling for the last 3 weeks to learn everything i can about PPI/DPI, Resizing images, GIMP, pixel wxh, file formats, megapixels, colorspaces etc. so I can get my stuff up there.
About a week ago after being totally lost I'm finally putting it all together. The one thing I'm hung up on is this. I resize my image on a google play app called Photo Editor, I size it to A2 Ya I even learned about International paper sizes and ANSI lol. I size it to A2- at 300 PPI. I have nice big A2 size 7-15MB files that MyOW's says are all around 30 mega-pixels.
So then I open that image in GIMP just to make sure its dimensions and resolution are correct (phone apps are buggy so) Here's something I noticed and I think it's important but I dont understand it.
I decided I would take the A2 about 16x22 inches 300 DPI file and save that as my medium sized image file. saved it.
Then i turned the Original file into an 8x10 inch at 600DPI.
And finally a Large size A0 about 33x46 inches at 150DPI.
Every time I converted the PPI/DPI and Dimensions it seemed like it wasnt taking long at all for GIMP to change the image like it would when i was experimenting with it trying to understand the process. It was almost instantaneous, it made me wonder,since i sized the original image at 300 dpi at A2 size- do I even need to make the small and large files? Like if I just uploaded the A2,file and they wanted a small size and they took it to their print shop/printed themselves an 8x10 inch would it appear to be/or even really be printed at 600dpi since its smaller?
And if they took it somewhere to print the A2 file at A0 size it would appear to be/or even really be printed at 150DPI?
Like is there some mathematical formula going on here where doing the other 2 files is pointless? Or should I go ahead and upload all 3 files- 1 for every size option for every image so I know the customer is getting the size they want at the quality I want them to be? Thank you so much mates, wish i had found this site 3 weeks ago. GL- W1TCH