Daz Renders and DPI

RexRed

Hello Daz peeps!

I have a few questions, I was hoping you could enlighten me on some suggestions and information...

My Daz renders are generally 10000 x 10000 32 bit rgb the largest resolution Daz will allow to render... But sometimes I render at 4k 3840x2160 they are also at 32 bit rgb. When I right click on them in Windows and go to properties > details it says they are 32 bit rgb and do not list the DPI....

For an 11"w x10"h coffee table book, would a 4k 32bit image work for a nearly full page spread? (enough room for title and captions underneath?) 

I have had a few images published in magazines before but I just got the largest resolution images I could get my hands on hoping they would be okay.

Using Photoshop how do I make sure the images have 300 dpi resolution? Wouldn't a 32bit rgb image at 4k cover that or should it be a few thousand bigger?

I am not sure how to do the math here... Any help on this would be very much appreciated. 

Thanks!

RexRed

Okay,

If we are talking dots...

If the printers want 300 dots per inch, in my mind a pixel is a dot. A pixel is the finest piece of resolution. 

If an image has 10,000 pixels horizontal, well, 10,000 divided by 300 is about 33.

So my reasoning is a 10,000 pixel image would print nicely on a 33 inch background for magazine print quality.

Likewise, a 4k image 3840 pixels horizontal divided by 300 = 12... so once again, in my mind it seems rational to assume a 4k

image would print nicely on a 12 inch piece of paper...

Is there something I am missing here? 

Leana

That's about right.

To get the pixel size you need you simply multiply the inch size by the dpi/ppi you want.

So 11"x10" at 300 ppi will be 11*300x10*300 = 3300x3000.

Fishtales

You're examples are correct although there is a difference between DPI and PPI.

https://www.scantips.com/lights/pixels.html

algovincian

RexRed said:

 

My Daz renders are generally 10000 x 10000 32 bit rgb the largest resolution Daz will allow to render...

I often see this stated, but it's incorrect. 10,000 x 10,000 are the default limits, but they can be changed. To do so, under Render Settings -> General -> Pixel Size (Global), click on the gear icon and click on Parameter Settings. Then uncheck Use Limits. Now you can set the resolution to whatever you wish.

As a practical matter, it should be noted that more VRAM is needed to render higher resolutions in Iray.

HTH.

- Greg

Nadalina

If we are talking about 2-page spread, you will need 6675x3075 pixels image, couple pixels more or less. That's at 300 dpi + 0.125 bleed, ideal for press. For press, 250 dpi is also fine, that would be 5563x2563 px. 225 dpi is still passable, that would be 5006x2360 px. For web 150 dpi is more than enough, it turns out 3338x1538 pixels. I calculated size for full two pages (22x10 inches), if there is space for captions and text, image will be smaller, but it is hard to know in advance how much. 

If you open new (empty) image in Photoshop at image size you want and 300 dpi resolution and then go to Image - Image size, you will see how many pixels do you need. If you change resolution with "Resample Image" turned on, you will see that pixels are changing too. When you render image from DAZ, it will be at 96 dpi, at least that's how my renders turn out. If you want to change it to 300 dpi without changing pixels, just turn off "Resample Image" and pixels will stay the same.

I don't know if 32-bit means something here, maybe is better quality so you could get away with smaller size and enlarge it in Photoshop. No idea, I am still usually working with 8-bit images.

Fishtales

Nadalina said:

If we are talking about 2-page spread, you will need 6675x3075 pixels image, couple pixels more or less. That's at 300 dpi + 0.125 bleed, ideal for press. For press, 250 dpi is also fine, that would be 5563x2563 px. 225 dpi is still passable, that would be 5006x2360 px. For web 150 dpi is more than enough, it turns out 3338x1538 pixels. I calculated size for full two pages (22x10 inches), if there is space for captions and text, image will be smaller, but it is hard to know in advance how much. 

If you open new (empty) image in Photoshop at image size you want and 300 dpi resolution and then go to Image - Image size, you will see how many pixels do you need. If you change resolution with "Resample Image" turned on, you will see that pixels are changing too. When you render image from DAZ, it will be at 96 dpi, at least that's how my renders turn out. If you want to change it to 300 dpi without changing pixels, just turn off "Resample Image" and pixels will stay the same.

I don't know if 32-bit means something here, maybe is better quality so you could get away with smaller size and enlarge it in Photoshop. No idea, I am still usually working with 8-bit images.

The 96 DPI is your screen resolution, mine comes back at 106 DPI :) I save mine at 0 DPI as for screen viewing they still only take up the same number of pixels no matter what resolution the viewing screen is. You only need DPI for printing which will depend on the printer being used and the size of print needed which would be the render pixel size divided by the print resolution or DPI. For a 40 feet x 20 feet billboard at 4 DPI you would only need to render at 19200 pixels x 9600 pixels but at 300 DPI it would only print an image 64 inches x 32 inches.

Leana

Nadalina said:

When you render image from DAZ, it will be at 96 dpi, at least that's how my renders turn out.

Actually it won't have any dpi information saved, so Photoshop will use the default for your system. 

Nadalina

@Fishtales, true, I was never thinking that pixels divided by dpi is size in inches. Maybe because my units are actually centimeters... anyway, I learned something new, thanks. And I didn't know about DAZ dpi information either, I thought it depends on some DAZ settings which I never bothered to look at. :) Thanks both of you, Fishtales and Leana.