Native 300 DPI Images VS Modified Images Using Phoyoshop

[VShaneCurtis]

Hi Guys,

I need some insights here.  I am a big fan of the band Rush and I'm currently trying to have a photo comforter made.  There are plemty of images available on the web.  All of them are low resoltion images. The seller from Etsy gave me image size requirements and resoltion requirements.  Resoltion is 300 DPI minimum.  So I loaded an image into Photoshop and increased the DPI to 300 and resized.  The file size is large as I would expect and it looks fine.   The seller says this method will not work.  She claims that it's not the same as a native 300 DPI image and the modified image won't work.   I don't get it.  300 DPI is 300 DPI any way you slice it.  What is she talking about?  What am I missing.  Additionally does anyone have any suggestions for a solution?

[rayek.elfin]

A PPI/DPI resolution given without an actual print size is worthless. What is the exact SIZE (dimensions) that are required?

And you can't just download a low resolution image from the web, increase the PPI/DPI and expect it to work: what counts is the actual pixel resolution, or details/information in an image. If you blow up a 500x500 pixel image to 5000x5000px in Photoshop the pixels will merely be blown up to blurry mess. If there are no details in an image how can you expect those details to be recreated/generated? Magic? Obviously that will not work.

The first thing to do is to change Google's image search parameters to find high resolution images only. Better, use Bing or Duckduckgo instead, because Google's image search doesn't display the image resolution anymore nowadays.

Change the search options to find high resolution (large/very large) images only.

Now notice that a few of the images are over 3000px wide and high - those could be used for a comfortor - probably.

Look at that: an image size of 4774 by 4561 px! That is quite decent. Download the high resolution image. At 300ppi/dpi it can be printed on paper at a max size of 40.42 by 38.616 centimeters. For a comforter this should be okay, because print resolution on a comforter's textile is much lower than on paper.

But for a bed sheet cover/comforter ideally you'd need around 7000 by 8000px, or similar. And PPI is completely unimportant here, because it means "pixels per inch" - 300ppi at the size of a comforter is WAY too high resolution.

In short: try to find an image of the band Rush at a minimum resolution of around 5000x5000px.

Any image below 2000-3000px is probably not going to cut it.

But to be absolutely certain about what the designer needs: ask for a minimum and maximum PIXEL resolution for width and height both. That will tell you what resolution you must deliver. PPI/DPI is a useless value in this case.

[VShaneCurtis]

Thank you for the clarification.  I understand that a high resoltion image is best and you have given me some alternate sources to look at.  Thank you.   Her requirements are: 8640 x 8640 pixels and 300dpi. for a Queen size comforter.  I will look at these alternate sites and see what I can find.   I'm considering multiple comforters Band Members, Neil specifically and a couple of album covers 2112 Moving Pictures and Signals.  Thanks for the help.

[rayek.elfin]

That's... quite a high resolution. The 300ppi is unimportant - only the pixel resolution is.

Good luck finding images at that high resolution on the web. Perhaps you have fotos that could be scanned? Or combine multiple photos into a collage.

Very best to you.

[TheDigitalDog]

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@VShaneCurtis wrote:

 Her requirements are: 8640 x 8640 pixels and 300dpi. 

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All you need is the first part; work in pixels! The other has no bearing. 

This very, very old primer on resolution still seems necessary to post, this may help in understanding what the printer clearly doesn't by their request:

http://digitaldog.net/files/Resolution.pdf

There is zero difference in a document that is 1000x1000 pixels (as an example) at 72 dpi (PPI) or 720 dpi (PPI) or any such value. All are 1000x1000 pixels and the dpi/ppi is simply a metadata tag. Your printer can do the same math about using the 8640 x 8640 pixel document you need to supply. 

[VShaneCurtis]

Thank you for the help.  I do have one question.  I always thought that DPI was related to how much an image could be inlarged before it becomes pixalated.  I didn't do a very good job of wording that, sorry.  Hope you understand the question.  From what you're saying DPI is meaningless.  No luck finding images as big as she wants so I think I'm out of luck.  I'm not paying good money for a comforter with a grainy picture.  Although your idea about combining images gives me some ideas.  Maybe the same image in a 4X4 grid or even different images might be an option.  A panel effect?

[D Fosse]

This is much simpler than you think. Pixels per inch, ppi, means exactly what it says: pixels per inch.

It's a simple formula for pixel density that determines how many inches of paper/comforter to spread the available pixels over.

If the file is 4000 pixels wide, and the ppi is set at 100 ppi, the resulting size is 4000/100 = 40 inches wide. That's all there is to it. It really is as simple as that.

And there is no way 300 ppi is needed here. 100 is more than enough. "300 ppi for print" is the most persistent myth in all of digital imaging.

Books and magazines are usually printed with a halftone screen frequency of 150 lines per inch. If you double that number, you reach the theoretical upper limit where it's no longer possible to discern the individual pixels in the halftone screen. Increasing the resolution further will not make any difference whatsoever. Anything above is wasted.

Then this number became widely misunderstood. It became a minimum requirement instead of a theoretical maximum.

But even so, this has nothing to do with sharpness. This is the limit for smoothness. The sharpness limit is the 150 lpi screen frequency.

And finally, there is no way a textile can hold that kind of pixel detail. I would think anything above 50 to 60 is wasted here, but let's just say 100 for good measure.

[Bojan Živković]

"The seller from Etsy gave me image size requirements and resoltion requirements.  Resoltion is 300 DPI minimum."

Wrong way to communicate with customer. You already have good explanations, your seller is communicating in wrong way with you. He should mention dimensions not resolution in PPI or DPI. Nothing wrong with you in my opinion, its seller mistake in communication.

[didiermazier]

Long story short : divide the width by 300 and you will get the real printable size (in inches).

I.E : 1920 px/300 : 6.4 inches wide.

Also check the preferences > Tech something and check the first box

Then when you will resample an image select this option in the dropdown menu.

Also Camera Raw has an option to enlarge; you can find it on the tree dots side menu. It will raise the resolution with less quality loss.

 

Hope it will help 

[VShaneCurtis]

Yes thank you for this.  The formula helps me to understand this issue better.  You have all been very helpful.   The image sizes she wants simply are not available.  I decided to do a "Four Corners" image as a test.  Here it is.  I have sent it to the seller.  Hopefully it will work for her.  Thanks again

[VShaneCurtis]

I do have one more question.  Given the seller's stated image size requirements what is the megapixel requirement that would be needed to produce an umage of this size?  I'm just trying to see what kind of camera would be needed here.  The seller claims that people usually send her images that will work.  I also spoke to her and she says my image quality is still too low.  I zoomed it to 100% in Photoshop and it looked pretty good.  Little or no pixalation. What do you think?

[davescm]

The last image you attached is still well short of the requirements you stated earlier in the thread. It measures 2048 x 2048 = 4.2 MegaPixels. You earlier stated the requirement was 8640 x 8640 =74.6 Megapixels.

One other thing to consider - do you have permission from the image copyright holder to use their image?

Dave

[VShaneCurtis]

Sorry I mistakenly posted the single image that I used to make the four corners image,  Attached is the image matching the seller's size requirement.  She claims that it is still blurry when zoomed.  I zoomed the image in Photoshop to over 100% and there was no pixelation.

[D Fosse]

It's been my experience that sales and customer relations people often know very little of the technical side of things. When I deal with printers I usually find a polite way to bypass them and talk directly to the people who will actually do the printing. They always know better.

I'm pretty sure the 4500-pixel plus image that rayek located above should be plenty good enough here.

Don't upsample to a higher pixel count. That is guaranteed to make the final result look worse than using the file as-is.

[VShaneCurtis]

Unforortunately my only POC is the seller.  So no such luck.