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Question

Image Size Resolution

Forum|Forum|6 years ago
July 10, 2019
9 replies
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Hi, I have a jpeg image photographed that has been supplied at 100% size at 350ppi however I need to tile this up to make a large image size so I need to scale by 10% of final size. I need the image to be 350ppi at 10% size but to retain the pixel data I need to uncheck resample which when scaled to 10% makes the resolution 3500ppi.

Images at 35ppi at final size for a 20m print should look fine however this looks more like 3ppi when I resample and when I don't resample its 3500ppi and 17gb file which does look correct. Please help me understand.

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T

Test Screen Name

Legend

This "more info" box - what is showing it? If this is Mac OS finder, its dimension is USELESS to you. This is not the size in pixels you may think it is! Just don't use Finder to check the size of a PDF, still less to check the resolution of an image in a PDF (remember, a PDF may have many pages, each a different size, with many images on each, each one of a different size).

Stephen Marsh

Community Expert

So you need a gravel background image that is 7 metres wide by 4.35 metres tall. You need to decide on a resolution for this canvas. This will likely be printed on a wide/grand format inkjet and usually viewed from some distance, however it may also be viewed "close". You will need to pick a lower resolution, you will not need 300+ pixels per inch. I'm guessing that somewhere between 25 to 50 ppi will be workable in file size, 70+ will start to become unwieldy.

I would try to create a seamlessly repeating tile as a source for a tiled pattern fill at the desired gravel print size, you can search for how to do this there are many tutorials, some better than others. Then perhaps use the patch tool to try to randomly break up the pattern a bit.

S

steveg73545872Author

Known Participant

Image below is the original jpeg at 350ppi and at 100% size.

Image below is taking the original jpeg, scaling to 10% (1:10) of finished size with resample unchecked, copied in to a Photoshop canvas size of 700mm wide (1:10) then placed in Illustrator where I have enlarged by 1000% to create a PDF to view at 100% size (Cropped from Finished size) with no resampling done.

Thanks

T

Test Screen Name

Legend

Hmm, on reflection, if you are placing in Illustrator why are you doing anything in Photoshop at all? Just place it, then scale it.

T

Test Screen Name

Legend

Also DO NOT choose No compression. Choose ZIP or carefully choose JPEG. That's just wasting space.

T

Test Screen Name

Legend

What says it will be 16GB, exactly?

What size is the PSD (I assume it's a PSD) you place into Photoshop (I assume you do PLACE it, not paste it?)

T

Test Screen Name

Legend

It will be pixellated in a PDF made by Illustrator because by default the resolution is reduced to 300 ppi. So your 3500 ppi comes back down to 300. Turn that off in Export settings.

S

steveg73545872Author

Known Participant

Thanks

I have turned off all downsampling however I cannot save the 3500ppi file as it will be 16GB

D Fosse

Community Expert

You're overcomplicating this.

Just uncheck resample and you'll be fine. Change ppi or print dimensions, whichever you want - the main thing is that as long as resample is unchecked, not a single pixel changes. And the file size will also stay exactly the same.

Ppi and print size are inversely connected. As one goes up, the other goes down, and vice versa.

S

steveg73545872Author

Known Participant

Thanks for the comment.

If I uncheck resample and change the dimensions to 1:10 of the current size then the DPI enlarges from 350ppi to 3500ppi. After this I need to change the Canvas size so I can duplicate the image and make one large background. By doing this I now have a 16GB file that I can't save and/or import in to Illustrator.

Thanks

JJMack

Community Expert

No all changing the Print Resolution does is change the size the pixels will be printed. The image Pixels are untouched. You have the same 8200x6000pixels the file should not change and your file should be nowhere near 16GB in size that would need to be saved as a PSB to be able to be that large.. Your image had nearly 50MP. If edited in 16bit color that would requite 6bytes of color data for each pixel uncompressed that image would only be 3GB of pixel data where are you getting this 16GB figure.

JJMack

S

steveg73545872Author

Known Participant

Hi,

Original is below however I want to scale this image by 10% of this size but retain the resolution at 350ppi so when I enlarge on the RIP at 1000% the actual resolution is 35ppi at final size (100%). Thanks

JJMack

Community Expert

There is no image there. It would be good if you provided some size information and wether the 10% scale is in the up or down direction. Printing a 350 DPI Print document at a 35 DPI will increase the print size 10x or 1000% I do not understand you need of interpolating the original image's Pixels up or down 10% before printing the actual print size you want. Or know what size that is only know it will be printed with a large pixel size a low 35ppi resolution.

In you first append you wrote something about tile. But failed state tile content or how tile will be used????

JJMack

S

steveg73545872Author

Known Participant

This is the original image size and resolution. I need to scale down to 10% (1:10) so I can duplicate the image and create a large file over 7m at final size hence the need to scale down to 10% size.

Below shows scaling down to 10% with resample off. However if I select resample and scale down to 10% size and the resolution is left at 350ppi then when I view at 1000% ( Final Size when enlarged) the pixelation is extreme.