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Upscaling from 300 dpi to 800 dpi

Forum|Forum|7 months ago
August 15, 2025
2 replies
1743 views

I am making a banner for a printer who is requiring it to be 800 dpi. I've never been asked for 800, it's always been 72 or 300, so I'm guessing this is something I need to learn in case it becomes the new norm. I've tried opening the original image in Photoshop, doing Convert to Profile > CMYK, making any changes to the photo I need to make, and then Image Size > constrain dimensions, Resample: Preserve Details 2.0, setting the resolution to 800, and then saving it. Then I embed the file into my main photoshop file, the printer's template, which is already 800 resolution using the same process as above. I've tried converting the images to smart objects, and as layers. There's outlined text, 3 shapes, a few .ai files for marks and the logo. Every time I submit it to the printer, it comes back saying: Resolution of color and grayscale images is lower than 799 pixels per inch, continuous tone image resolution lower than specified. I don't understand how to fix this so they will accept it. Can anyone please help? I greatly appreciate your ideas!

Stephen Marsh

Community Expert

Image content (photographic, text etc) viewing distance/conditions and scale factor all play a role.

What are the original pixel dimensions before you resample to 800ppi? What is the physical print size in CM or IN?

You can take a look at the following script;

https://community.adobe.com/t5/photoshop-ecosystem-discussions/photo-blow-up-question/td-p/14416674#U15306592

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wendi_4742Author

Participating Frequently

One of the original image files is 10.2 MB, 300 res, 5760px wide and 3840px high. I feel like that should be ok but for some reason, they are telling me it's not big enough. The only information I can find on making an image larger (which I was always told you can't do) is to go to Image > Image Size > keep the dimensions proportional, change resolution to 800, check Resample: Preserve Details 2.0. I tried that but it didn't work for the printer, they said I was just reducing the quality of the image. But there's no other way that I can find to make an regular hi-res image so large.

D Fosse

Community Expert

This feels all wrong. That image is big enough for any practical purpose. Someone has misunderstood something here. A banner, in the sense of a physical large format print, never needs to be anywhere near this resolution.

Viewing distance is a function of size, because the eye needs to take in the whole. The bigger it is, the lower the required ppi because it will be seen from farther away. A big wall-sized banner can be as low as 10-15 ppi and still look crisp and sharp.

Here's an illustration I made a while ago to illustrate this, which I've posted a few times:

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ExUSA

Legend

Banners don't need to be printed at 800 PPI. Typically, printed material viewed at a distance is much lower resolution, for a banner, likely somewhere in the 100-150 PPI range should be plenty. Even high-end gravure or offset printing doesn't need to be above 600 PPI or so. Banners will be printed on a large-format inkjet and materials such as canvas or vinyl can't display very high resolution images.

Having said that, Image->Image Size is where you change dimensions (total pixels) and resolution (how those pixels are divided up.)

A banner printed at 800 PPI would have to be HUGE. Let's say for example that it is 8' x 3', or 96" x 36". That would mean your file would be 76,800 x 28,800 pixels or 2+ Gigapixels.

I'd go back to the printer and get some realistic numbers. Also find out whay they are using Photoshop instead of Illustrator? That is better suited to designing banners.

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wendi_4742Author

Participating Frequently

This is exactly the problem. The file size is so large that my work computer was barely moving, so I've switched to my personal Mac and am redesigning it a fourth time to see if it will work. I've called and emailed the printing company and both of the representatives I spoke to said it needs to be 800res or it will look pixelated and they can't tell me how to make that happen except that maybe my 300res professionally taken photos just aren't big enough. One of the original image files is 10.2 MB, 300 res, 5760px wide and 3840px high. I downloaded a template from another printer and it says the same thing: "A miminum resolution of 800 dpi on any other material (i.e. vinyl, rigit materials, etc.) is required for all raster images. Higher resolutions are preferred." The template is 1:10 scale and it says not to resize it. I called some graphic designer friends and they've never dealt with this. I've designed retractable banners before and they were 300 resolution and looked just fine. When I open the original image in photoshop, I go to: Edit > Convert to Profile > CMYK. Then I use the brush tool to get rid of something in the image. Then I go to Image > Image Size > keep the dimensions proportional, change resolution to 800, check Resample: Preserve Details 2.0. Then I save it as a .psd and go back to the main file in Photoshop, Illustrator or InDesign (I've now wasted over 20 hours redesigning this file so many times), and place it as an embedded file. Then I have to create a clipping mask to insert the image into a shape and create outlines on the text. Then I export or File > Save As as a Press Quality PDF, checking the Preserve Photoshop Editing Capabilities box. The exported PDF is going to be HUGE.

Stephen Marsh

Community Expert

What is the intended viewing distance of the large format print? 1 metre, 3 foot etc?

Are you working at 1:1 scale, or half or quarter size? If working at half size and the effective resolution was 400 PPI, then the upsized output would be 200 PPI.

What is the physical size of the image in InDesign and what is its effective PPI resolution?

What have you set in your PDF export settings for resampling over a specific (effective) PPI threshold?

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