# Ideal DPI for a projected image?



## BananaRepublic (Mar 20, 2016)

An image I have will be put for viewing on a projector, I don't know what brand or anything but I do know min dimensions are 1600 pixels on the long edge. What is the idle DPI for this situation does anyone know I have read 160 but I don't know is it better to just leave it at 300 and be done with it.

Thanks


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## KmH (Mar 20, 2016)

There is no DPI for that situation, ideal or otherwise.
Nor is there any PPI.
One PPI or 10,000 PPI - the image won't display any differently.

Only the image resolution - pixel dimensions - count.

You'll want to be aware of what aspect ratio image the projector delivers.


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## BananaRepublic (Mar 20, 2016)

KmH said:


> There is no DPI for that situation, ideal or otherwise.
> Nor is there any PPI.
> One PPI or 10,000 PPI - the image won't display any differently.
> 
> ...




All we have been told is that the min image size is:

Photos must be a *minimum* of *1600 pixels on the longest side*.
Perhaps I miss quoted the info originally. However I do know the projector is not fit for purpose based on images Ive seen before. Sadly its a club thing so the powers that be have no intention of finding something better. I think it may not exist at least on the high street/office equip level.


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## snowbear (Mar 20, 2016)

Both are 1600 pixels on the long side (thumbnails displayed).  One is 100 DPI, the other is 1200 DPI.


 

Older projectors (and probably some newer ones) are terrible for viewing high-definition images.


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## BananaRepublic (Mar 20, 2016)

snowbear said:


> Both are 1600 pixels on the long side (thumbnails displayed).  One is 100 DPI, the other is 1200 DPI.
> 
> View attachment 118084 View attachment 118085
> 
> Older projectors (and probably some newer ones) are terrible for viewing high-definition images.



Thanks Bear


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## GHK (Apr 8, 2016)

Studio 101 is quite right; I know that a specification for dpi is often quoted as being required but it is totally irrelevant.


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## weepete (Apr 8, 2016)

I've seen images projected at 72 dpi, we were very close to the projector and still look awesome so I really wouldn't worry about it.


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## GHK (Apr 9, 2016)

This is NOT relevant; they would have looked EXACTLY the same if the dpi had been change to some other value provided that you didn't alter the pixel dimensions at the same time.


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## GHK (Apr 9, 2016)

BananaRepublic said:


> An image I have will be put for viewing on a projector, I don't know what brand or anything but I do know min dimensions are 1600 pixels on the long edge. What is the idle DPI for this situation does anyone know I have read 160 but I don't know is it better to just leave it at 300 and be done with it.
> 
> Thanks



I think that you have either been misled or have misinterpreted the requirement.
I think that you will find that it is a MAX of 1600 pixels.
Digital projectors have a stated maximum display size.   If the one you use has a max of 1600 it must be a fairly modern one.   Displays have increased very slowly in size over the years; my very old home one has a max of 800 x 600.   1024 x 768 later became more common and many exhibitions still use that size.   My club and federation now use 1400 x 1050, which is the largest I have come across myself.   Larger sizes are most probably meant for large halls and I should think that they are very expensive.
Another point is that the larger of the two dimensions only applies to the horizontal edge; the smaller figure is the max for the vertical side.
If you supply an image with less than the projector's native res. it will not use up the full available space and will look small on the screen.   If you send an image with more than the p.n.r. the projector is programmed to downsize it to fit, but this is not advised.   It is better to do the downsizing yourself as you will almost certainly be able to make a better job of it than the software that is built into the proj.
Another tip:  I often find that after sizing an image to 1400 horizontal, the vertical is less than 1050.   If this is projected there will often be unsightly bands above and below the image.   I always eliminate these by changing the Canvas Size to 1400 x 1050 with Background set to Black.   The on-screen image then looks much cleaner.
GHK


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