image resolution..

[shikodesign2000]

Hi,

 

I just want to know how to raise the resolution (dpi) of an image ?

 

I rendered an image 1500*950 in max, then I checked it in photoshop in the (image size dialog box), I found the resoulution= 72 pixels/inch, so I changed to 300 pixel/inch

to know the relevant dimensions for the new resolution, it was 6250*3958

 

I re-rendered the image with that dimension in max, then I opened in photoshop, but I found the resolution in the (image size dialog box) =72 pixels/inch!!!!! how is that?

[STRAT]

re-check the physical size. you're getting confused between pixel size and physical size.

 

6250*3958 pixels is 6250*3958 pixels whatever the dpi is. but, depending on the dpi value, 6250*3958 will give different physical dimensions.

 

'what size do i want the final image printed at?' is what you ask yourself first. then render at an appropriate size that satisfies this question.

[shikodesign2000]

Ok, but how can I know the resolution (? pixels) * (?pixels) that gives 300 DPI??

[STRAT]

there isn't. you're missing the point.

 

300 dpi could mean 1600 pixels, 800 pixels, 689453298 pixels etc etc.

 

 

ie -

 

300 dpi @ A4 = 3508 x 2480 pixels

300 dpi @ A3 = 4961 x 3508 pixels

 

http://en.wikipedia.org/wiki/Dots_per_inch

http://www.frameworkanimation.com/ClientZone/Resolution.html

 

http://forums.cgarchitect.com/5759-printing-resolution-size-dpi-ppi.html

 

 

[CJI]

Thats why i hate high resolution. It eats render time but without it you can't see all the detail i put in to my white wall shader!!! Can someone invent digital paper with optical zoom please. Thankyou. lol

[JonRashid]

There is a print assistant in Max to help you. You need to know at what size the image is to be printed first. You then factor your dpi in and that will tell you how many pixels you need to render at.

[shikodesign2000]

Ok my firends, can anyone tell me if there's an option to transform the 72 dpi to 300 dpi?? forget about the resolution in pixels..

[STRAT]

why? again, you're missing the point. you cant forget about pixels, as it's utmost important. it goes hand in hand with resolution when deciding the final output size.

 

you can easily size your 72 dpi image up to 300 dpi in photoshop for example, but to what end? you'll only loose quality if you havent taken the pixel resolution into hand first.

You must first determine what size you want to print out at. say A3 size at 300 dpi.

 

 

for A3 at 300 dpi =

 

A3 is 16.537 X 11.693 inches, now multiply this by 300 (dpi) -

16.537 X 300 = 4961 (pixels) and 11.693 X 300 = 3508 (pixels)

 

so you render at 4961 x 3508 pixels from max. open this image in photoshop and it shows 4961 x 3508 pixels at 72 dpi, but crucially at 175 x 123 cm. This equates to 42 x 29.7 cm at 300 dpi.

[pfbreton]

Here is how I do it:

 

http://screencast.com/t/NWM1MmMyNW

[Nic H]

i dont understand what it going on?

its very straightforward

 

use the printsizewizard if you are stuck

[STRAT]

i dont know.

 

if you've never had to consider or think about pixel res V's DPI before or even what it all means, then it's a difficult one to get your head around initially. as proven.

 

it's like a typical printer - they phone up saying everything must be provided at 300 dpi. this is the only phrase they know. but they havent a clue what it means or what actual size they want. just 300 dpi. wtf? it's quite funny to listen to sometimes.

[CJI]

Your still missing the point. DPI is in relation to printing. You cant forget about the pixel resolution as all prints have a resolution in pixels that make up the image. DPI is just the amount of information in a square inch.

 

An A4 piece of paper is 210mm x 297mm

at 72 DPI it takes 595 x 842 pixels to make up the dimensions of an A4.

at 300 DPI it takes 2480 x 3508 pixels to make up the the dimensions of an A4

 

If you were to render them both they both come out as 72 dpi images as thats all that monitors can display. Its when you print the 300dpi comes in to effect.

Hypothetically if print resolution had no impact on quality when printed natively the one at 72DPI and the one at 300DPI would be exactly the same.

 

So no there is no option for 300 DPI its all in the resolution of pixels. On screen pixels are abstract and have no actual dimensions. Its only when it comes to printing that pixels take on dimensions.

 

At least thats what i know.

[CJI]

oops i seem to have overlapped with strat. Thats what happens when you don't refresh you see. Sorry about the posting of the same info.

[Stephen Thomas]

The only image format that actually stores the DPI information is TIFF, as far as I know. But like the guys already said, all this value does is control the default size for printing. If you render your file to TIFF format a dialogue box appears in Max to allow you to input the desired resolution.

 

However it is very important that you also calculate the image size first so that your image is the correct size for the final print output. As already noted the print size wizard is your friend here. If you already have the image rendered and want to 'bake' this resoluion into the file then change it in Photoshop and re-save as a TIFF. Make sure that it is of sufficient size first though.