Print resolution... how?

Fri May 23, 2014 11:36 pm

So, a client asked for a 300 dpi renders, and I don´t know how to produce that depth. Where is the setting to change de dpi of the final render, if it exists?
I tried to set a custom dpi setting in the white point, as you see in the screenshot, but it still produces a standard 72 dpi image.

Fri May 23, 2014 11:52 pm

UPDATE: I have found a setting in the preferences panel where you can raise the dpi value... but it still produces 72dpi images. I don´t know what to do

Fri May 23, 2014 11:56 pm

For what I understand, DPI doesn't mean anything. It's dots per inch (or actually, PPI, pixels per inch in this case).

All it does is tell the printer how big to physically make the image. If the image is 1500x1500 pixels and you print it at 5x5 and at 10x10, its the same image, just printed larger.

In Photoshop, make an image that is the physical size they want and at 300 resolution. this will tell you the pixels you need to make that image.
Render your image at those dimensions. Then just go into photoshop and change the resolution to 300 and then change the physical size to what it should be. Notice that the pixels do not change. All this does is tell the printer to physically print it smaller, making it have more definition per inch.

It's pretty common for people to think this does more than it actually does. I don't think it has any effect on digital images. The pixels you are making the image is what is important.

Sat May 24, 2014 12:18 am

So, if I understood well:

I need a 2100x2100x300 dpi image

-I create a new document in photoshop: 2100x2100x72
-I increase the dpi setting to 300, then the size changes to 8750x8750
-I render in Octane the image at 8750x8750, save it and open it in photoshop
-I change the dpi setting to 300 and manually, the size to 2100x2100

Would that be the procedure? So, what is that dpi setting in the Octane preferences good for? I must be missing something.

Sat May 24, 2014 12:22 am

Pixels are pixels.. if client says 8.5" x 11" - this is just a matter of 8.5 x 300 = 2550.. and 11 x 300 = 3300... never needs to be any more difficult than that.

Just note that when you do need to figure out pixel dimensions, be sure to uncheck Resample Image in PS Image Size dialog (ctrl+shift+i)

EDIT: we must have posted at same time.... no no no paqi.. you are getting things very confused. Like I say above, pixels are pixels are pixels... If client says inches, you just multiply 300 times that and set this res in Octane. If client provided pixel dimensions, than obviously you just pop those in - but if you needed to know the inches that this is, then you just divide 300 and that is how many inches.

In other words, you can never set a 2550x3300 render to be at 300 dpi. It is physically impossible. But a 2550x3300 render is 8.5x11 @ 300 dpi... An image can only be its width in pixels by height in pixels, and this never changes regardless of what dimensions/dpi is.

Go in PS and open an image you already have somewhere. Uncheck Resample Image and play around with Document Size settings (width or height) and watch the resolution change.. this is a great way to quickly understand how dpi works.

Sat May 24, 2014 12:28 am

Your client is asking for 300dpi renders, but what they're really asking for is an image that has the resolution to print at 300dpi. The only thing you need to worry about is final pixel dimensions. If they know what size that is, great. If they don't, ask how big the final print will be in inches. Then multiply that size by 300 and you have your pixel dimensions. So an 11"x17" print @ 300dpi would be a 3,300 x 5,100 pixel render.

Hope that helps.

EDIT: Looks like I'm repeating information.

Sat May 24, 2014 12:55 am

Unfortunately, a lot of people (even graphic artists) don't understand this and will try to tell you it needs to be at 300 DPI ect ect. Don't let it phase you, just ask for the overall dimensions and figure out the pixels you need. If they arnt printing it, the DPI literally means nothing.

I've gotten into arguments with my design teacher when I was in school because she thought it meant way more than it actually did.

Sat May 24, 2014 1:01 am

ok ok, I´m not very used to work like that, that´s all. The client wants it to be 7 inches x 7 inches at 300 dpi. That will be 7x300=2100 pixels. My fear was is they load the image in photoshop to check the dpi to find it´s in 72 dpi. So if you are correct, I just render a 2100x2100 image, and manually change it´s dpi in photoshop to 300 without resampling it.

Sat May 24, 2014 1:39 am

Be sure to ask if they need bleed though paqi.. In the print world, this is often between 1/8 - 1/4 inch... so for that 8.5x11 with 1/8" bleed, it would be 8.625 x 11.125 @ 300... not trying to complicate things.. but this could save you some grief, if your client was assuming you would be providing bleed and didn't.

Sat May 24, 2014 3:25 am

PAQUITO wrote:ok ok, I´m not very used to work like that, that´s all. The client wants it to be 7 inches x 7 inches at 300 dpi. That will be 7x300=2100 pixels. My fear was is they load the image in photoshop to check the dpi to find it´s in 72 dpi. So if you are correct, I just render a 2100x2100 image, and manually change it´s dpi in photoshop to 300 without resampling it.

Don't worry, DPIs name gives the impression that it's a setting you need to deal with, but it isn't. You're correct, a 2100px square image, when printed at 300dpi, will measure 7x7. It's up to you if you want the change the dpi in Photoshop for them. Seems to me that if they're the ones handling/printing the image, they should know enough not to be fooled by "72" on the screen, but who knows.