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it is not all about dpi

natj

New Member
i am really newbie at printing but we bought a printer machine and printing canvas wall arts.
we got images that some 300 dpi and some 72 dpi.
one of the 300 dpi image has 3000x2000 resolution but with that i got really bad output with 100x140 priting.
but also when if i have 72 dpi with the 3000x5000 resolution, then i will get really good output with 100x140 printing.

anyway i am wondering, can i make the photos better quality? i know that this 300 dpi(3000x2000) images is the best quality one and i have it but couldnt get good output with 100x140.
how people can get the better one with the same images that has same quality?
is there any trick? maybe photoshop things to increase the quality of images?

can you help me guys. i dont get the issue here.
we are new at printing.
 

Solventinkjet

DIY Printer Fixing Guide
It depends on what size you printed those images.

3000x2000 @ 300 dpi = 10" x 6.66"

3000x5000 @ 72 dpi = 41.66" x 69.44"

Printing at their native size should produce good results in both. But let's say you enlarged the 300dpi image in the x axis to match the 72dpi image size. We would have to enlarge it by a factor of 4.166 and decrease the DPI by the same factor. So 300 / 4.166 = ~72.

You might think, if both are now the same resolution and size, why did the 300dpi image print junk? Because the enlarged image is trying to portray 300dpi worth of information in only 72dpi. Just by enlarging the image without any special algorithm, filters, or processing, the computer can't fill in the gaps because it doesn't know what information to fill it with.

There are pieces of software that attempt to fill in the gaps in information due to enlarging and some are better than others. I think Fred Weiss had a post about an AI based one a few years back. Maybe he can enlighten us on that. In Photoshop when enlarging make sure to use the Bicubic Smoother resample option for better results as well.
 

natj

New Member
It depends on what size you printed those images.

3000x2000 @ 300 dpi = 10" x 6.66"

3000x5000 @ 72 dpi = 41.66" x 69.44"

Printing at their native size should produce good results in both. But let's say you enlarged the 300dpi image in the x axis to match the 72dpi image size. We would have to enlarge it by a factor of 4.166 and decrease the DPI by the same factor. So 300 / 4.166 = ~72.

You might think, if both are now the same resolution and size, why did the 300dpi image print junk? Because the enlarged image is trying to portray 300dpi worth of information in only 72dpi. Just by enlarging the image without any special algorithm, filters, or processing, the computer can't fill in the gaps because it doesn't know what information to fill it with.

There are pieces of software that attempt to fill in the gaps in information due to enlarging and some are better than others. I think Fred Weiss had a post about an AI based one a few years back. Maybe he can enlighten us on that. In Photoshop when enlarging make sure to use the Bicubic Smoother resample option for better results as well.
thank you for replying. i will look at bicubic on photoshop
 

Fred Weiss

Merchant Member
I'll be happy to do an enlargement or two using the AI enlargement software I have. Just email the image to the address in my signature along the pixel dimensions you would like.
 

chinaski

New Member
A common misnomer, but by DPI (dots per inch) you mean PPI (pixels per inch). Dots refer to printer droplets and not pixels. By itself DPI doesn't really necessarily mean much in terms of quality. Pixels are an indication of quality, but certainly not absolute.

PPI, on the other hand, refers to the internal resolution that is being displayed on your screen. Pixels can by subdivided, but that doesn't increase quality. You can set the PPI to 1 (no-downsampling checked), and print a 5000x3000 pixel image and it won't make a difference (Pixels=Data). (PPI= how big you want to display image on your screen.)

Think of it as taking a pie with 4-pieces and cutting those pieces in half to create 8-pieces. You still have the same absolute quantity and the quality of the whole hasn't changed.

A better way to judge quality is to set your resolution in photoshop to match your monitor (in my case it's 218ppi). Here's a useful website to do so. https://dpi.lv/ Then set (image size) followed by (view—>print preview) This way you can view all images on your screen at the exact size you intend to print them at and visually assess quality in ways that numbers cannot.
 

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natj

New Member
guys you are awesome enlightened me. i will check out the "Topaz Gigapixel AI" first and learn something about dpi and ppi :) thanks guys.
i can buy actually if i get the best quality that i want.
 

chinaski

New Member
Photoshop 2021 has a new feature called "super resolution" which is supposed to be a major improvement from their previous resampling software —Might be worth checking out.

What RIP are you using? I find Caldera does a fairly good job in resampling. Although, I find resampling improvements are somewhat marginal.
 

natj

New Member
i use ultraprint and printexp to print.
with the first one i rip the image and the other one print.

i dont know other things service of printing machine loaded this programs and i am using. actually i dont know if i can use different one than servicer loaded.(ultraprint, printexp) i dont know much things. really newbie at this but today learnt really much.
i will check out super resolution too. i will try everything as much as i find. :)

actually when i am searching topaz gigapixel al, i found letsenhance.io and like it. it gives me good resolution. now i downlaod trial of topaz will try a few minute.
 

MacD

New Member
I have been in the offset and digital printing world for a long time. And have not really taken the time to understand all of this. But as far as text and logos go vector art is the best and will enlarge without any issues. As far as rasterized art goes like pictures and text/logos saved as say a jpeg it depends on how it was created I think some people open a new job in Photoshop with 72dpi settings instead of opening a new file at 300dpi they just don't know. I personally will use InDesign or Illustrator to setup jobs with text or graphics and import the photos into them and then export as a pdf or high res jpeg or png. Second if it is a bad photo at 300dpi then it will print bad. If it is a good photo at 72dpi you normally get an ok image. I can normally tell by zooming in close and looking visually at how rasterized it looks. I have seen low reseloution images look pretty smooth. But some you zoom in and what I call the giggittes is terrible. I have found a program called Qimage dose a good job of resampling they call it image interpolation for enlarging images. It will not make a bad photo good but will enlarge without getting worse in my opinion.
 

natj

New Member
i got help from Fred Weiss gave me 2 different output one of it was from ps and other was from Topaz.
if i get them in order it would be topaz would be the best one and after coming ps and last one is ofc original one.

i zoomed the all three images and it gave me good output.
anyway i download topaz trial one and tried it gave me really good outputs. i am really happy to open this topic. i am so appreciate to all you guys. you gave me a hand :)
 
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