Vray Render to Photoshop

Hello everybody.

I have situation currently… No matter what size of Render I renderize in Vray, when I open the JPG file in photoshop, its resolution is always 72

How can I increase it? I am aware increasing an image’s resolution in photoshop makes up pixels to fill in the space. So that why I want to increase the resolution via Vray.

A rendered image is only pixles, so to print the image the computer needs to know how big those are going to be on the paper, that is where dpi comes in, how many dots (pixles) are going to be used per printed inch.

In photoshop you can alter the dpi value and choose to resize the actual pixles, or just alter the dpi value without resizing the actual image. If you just alter the dpi value you will see that the width and heigh values in inches (mm or pt depending on your setup) are automatically adjusted accordingly.

Some background info:
72dpi is an old default used back in the days where most computerscreens were crt and had about 72 pixles per inch in physical size, and this default is added to an image when saved when no setting is applied from the application. As far as I know V-ray does not give you an option to set another value. This was normal for most renderers back in the days since all they do is making colored pixles and the user had to alter this when and if they wanted to print the image to a fixed size.

My rule of thumb is to use 100 dots per cm
(I don’t use inch as a measurement since I am in Europe)
And that makes the math easy to do in the head, an A4 paper size is 29.7x21 cm and therefore needs 2970x2100 pixels. This gives a print resolution of 254 pdi which can not be told apart from 300 dpi by the naked eye.

Good luck and happy rendering and calculating :wink:


Thanks for your reply.

Im afraid I dont understand completely. Suppose I have a render of 1600x1200 with pixel aspect ratio of 1.0 and image aspect ratio of 1.3333 (v ray defaults)

Now I save as JPG.

Open photoshop and a A3 size canvas. I then copy my image to the canvas.

The canvas has a resolution of 300 but the image has a resolution of 72, so the size of it is going to be very little. I need my image to be 25cmx25cm

How can I make sure the resolution is 300dpi aprox?

It’s very simple. Pixels do not have a dimension - they are whatever size you set them to be.The only thing that really counts is how many of them you have relative to the size you want to have your image. Too few and you will actually perceive the dots, too many and you are overloading your system uselessly (you won’t be able to tell the difference)

If you have an image that is 1600 pixels wide and you want to print it at 25cm, the pixels per cm will be 1600/25 = 64.

For dpi (dots per inch), that will be 64*2.54 or around 160dpi. So your 1600 pixels are not enough if you want 300 dpi in that size of image.

Therefore, if you want to have an image that is 25cm wide at 300 dpi, you need to work backwards to find how many pixels you really need.

25cm * 300dpi / 2.54cm per inch = 2950 pixels approximately - say, 3000 for a nice round number.

HTH, --Mitch

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Thanks you for the math! Now everything is much clearer.

Though V rays max resolution is 2048x1536 :frowning:

Is that an edu version? I though that they had removed the resolution limitation quite awhile ago…


My bad, thats the maximum default resolution. I can input a custom one


Why are you using jpg as output for Vray? Jpg is very low quality and it does not save layers. If you save tiff or higher you can utilize the layers that Vray provides, such as lighting, materialID, background and many others. This gives you the opportunity to select parts of the scene and improve lighting, curves or whatever trick PS provides. It will greatly improve your renders. Look for ‘vray for rhino compositing’ on vimeo.

You are totally right! Thanks for the recommendation. Still, for printing I should save as JPG right?

I use PNG for high quality files, it supports transparency and is loss less and can be read by anything.
Or JPEG for everyday renders, at 100% quality.