300 dpi exr output

[Image Box Studios]

Hello Corona guys,

I am exporting my render output in .exr format on 3000 px. When i open my exr render output in Photoshop, it shows 72 dpi resolution. How can i get 300 dpi resolution on 3000 px image size.

Thanks in advance.

[Frood]

It´s just a default photoshop value because ppi ("dpi" does not apply here because it´s output/printer dependend) is unknown. If you want to have 300ppi displayed in PS (why? It does not change pixel resolution or the image at all, it´s just part of the equation pixel/size=ppi) then do in PS:

Image -> Image Size -> untick "Resample" -> change resolution to 300 pixels(!) per Inch -> done. The image is not resampled this way but you have a different ppi value in the document.

The only advantage to do this is, that it may be more convenient when placing the image in some kind of layout application because the initial size is closer to what you want to have, but usually the size is adjusted anyway after placing.

You can´t set the ppi value directly from max and afaik exr does not even has some metadata for ppi or dpi.

Good Luck

[Image Box Studios]

It´s just a default photoshop value because ppi ("dpi" does not apply here because it´s output/printer dependend) is unknown. If you want to have 300ppi displayed in PS (why? It does not change pixel resolution or the image at all, it´s just part of the equation pixel/size=ppi) then do in PS:

Image -> Image Size -> untick "Resample" -> change resolution to 300 pixels(!) per Inch -> done. The image is not resampled this way but you have a different ppi value in the document.

The only advantage to do this is, that it may be more convenient when placing the image in some kind of layout application because the initial size is closer to what you want to have, but usually the size is adjusted anyway after placing.

You can´t set the ppi value directly from max and afaik exr does not even has some metadata for ppi or dpi.

Good Luck

Thank you very much for your message but i am looking for some information on dpi not ppi. Actually my client need images on 300 dpi for print purpose. So my question is how can i get 300 dpi for printing purpose on 3000px. i can save tiff image in 300 dpi but i can not find a way to save .exr file in 300dpi. Actually its a exterior render image and exported in exr format because with exr option i can easily add sky in background.

[romullus]

You won't give to client exr file anyway, so why bother with dpi? You can add needed dpi after you convert file to tiff or some else format.

[Frood]

i can save tiff image in 300 dpi but i can not find a way to save .exr file in 300dpi.

As mentioned: EXR has no mechanism to store this information. You could teach your client about the relationship of ppi/dpi, image resolution and size maybe? And: "dpi" just does not exist in this stage of production, it´s a value related to print.

Your client get´s exact the same image regardless of the ppi/dpi value displayed in PS, no data/resolution loss or whatsoever.

Good Luck

[Image Box Studios]

You won't give to client exr file anyway, so why bother with dpi? You can add needed dpi after you convert file to tiff or some else format.

Of course, but these images are for printing purpose and are going to on a bill board. and if my image dpi is 72 and according to you,i should convert 72 dpi to 300 dpi in Photoshop manually , i am afraid that my image will loss resolution and quality and after 72 to 300 conversation my image height and width will change too.

[romullus]

You won't loose anything. Read this carefully:

Image -> Image Size -> untick "Resample" -> change resolution to 300 pixels(!) per Inch -> done. The image is not resampled this way but you have a different ppi value in the document.

[Frood]

i am afraid that my image will loss resolution and quality

It will not. Read the posts again or try it yourself. Just unckeck "Resample" in the image size dialogue. Pixels will not change at all as I already wrote. It´s just some metadata in the document, nothing more.

and after 72 to 300 conversation my image height and width will change too.

Yes, that´s the intention of ppi/dpi. See: You have 3k pixels width for example. If you have 100ppi, your document size will be about 30 Inches. If you have 300ppi, your doc size will be about 10 Inches.

In both cases, your image has still 3000 pixel in one direction. See this equation:

ppi=pixelcount (pixels)/width (inch)

In your case, "pixelcount" will be always the same, it´s the constant. So when you alter ppi then width (size) has to change.

Good Luck


@romullus: You won this time ;)

[romullus]

1:1 :]

[Ondra]

I ran fulltext search on EXR technical specification and there is no mention of DPI or PPI. When I google EXR DPI, this thread is the first thing that pops. It almost looks like EXR has no official way to even store DPI information since the format was created for VFX where it is basically useless...

[Image Box Studios]

Got it. Thank you very much guys for your fast support and replies. Really appreciable.

[Frood]

When I google EXR DPI, this thread is the first thing that pops.

It´s actually this one:

https://forum.corona-renderer.com/index.php?topic=7518.0

which is basically in fact almost the same :]

Good Luck

[Juraj]

Ah, tha famous DPI/PPI, the singular topic where artists are equally *dumb* as their clients :- )

I used to answer this question at least 5 times a years on cgarchitect, but...it never saves the world.

Great answer by Frood !  You should have stopped after the first, people need to use google instead.

[maru]

I'm a having a deja vu after a deja vu! :)
https://forum.corona-renderer.com/index.php/topic,12414.msg80006.html#msg80006

[Frood]

Yes Maru, but your link is about real upsampling and ppi in general if clients get crazy about absolute resolution and the usual 300dpi slipslop - something different.

Good Luck