dots per resolution unit

General questions about Indigo, the scene format, rendering etc...
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daniel_nieto
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dots per resolution unit

Post by daniel_nieto » Fri Apr 13, 2007 4:00 pm

is there a way to change the default 72 dots per resolution unit to an arbitrary number? (obviusly above of 72?)

cheers! :) and sorry for my stupid questions.
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Post by Zom-B » Fri Apr 13, 2007 4:21 pm

polygonmanufaktur.de

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Post by daniel_nieto » Fri Apr 13, 2007 4:46 pm

ok, maybe the question was not appropriate, i asked it because once i made my girlfriend an image in photoshop, with the default options, and i wanted to gave it to her printed but not in paper, but photografic paper, so i went to this place where they print posters and stuff, and i gave them my JPG image, then i asked for the largest print they could do, (my image was 966 x 756) and they said the largest print they could do is like 15cm x 10cm (6.25in x 4.1in), and they justificated that saying: if you had done this with more "PPI" we could printed it larger...

so that's my story, i dont know if the guys that was printing there was trying to refer to the "resolution" or he didnt know what he was talking about when he said PPI, well in this case, i believed him... sorry... so, for a bigger print i just have to render it with more resol?
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Post by StompinTom » Fri Apr 13, 2007 4:58 pm

DPI (or PPI) means dots per inch (or points per inch).
screen resolution is usually 72 DPI (sometimes 96 or so).
print resolution is usually around 300 DPI for photographs, small scale stuff and much lower for posters (viewed from farther off).
therefore, doing the math, youre onscreen size should be ~4.2 times bigger than the size you want it printed (300/72).
OR
you can take your picture into photoshop. under image, hit image size.
change the DPI to whatever print resolution you want (~300 DPI) and uncheck 'resample' or whatever so that it doesnt actually resize the picture but just changes the resolution. it will show you the size (in inches or cm) that the picture will be with the resolution you just set.

so "to change the default 72 dots per resolution unit to an arbitrary number" just use photoshop. its got nothing to do with Indigo.

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Post by daniel_nieto » Fri Apr 13, 2007 5:59 pm

oh thanks stompinTom! im planning print some future renders, so i will do that thanks!
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Post by joegiampaoli » Fri Apr 13, 2007 8:41 pm

Thats right, just take the image into any image program, resample the dpi to 300 without rescaling, image in monitor will be the same but printing size will be higher, for best results save your image to tif format, which is a printing format that accepts CMYK values if you want to print in professional format (like magazine paper etc...)
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Post by m1j » Sat Apr 14, 2007 2:47 am

When planning to make a print of an image the final size of the print sets the pixal size of the image. If a poster is the aim the original digital image needs to be large. A resolution of 3000x4000 would be good. The DPI only tells the printer how to stretch the pixels in the image. It has not real affect on the image. A single pixel image with a DIP of 0.1 would be a solid color 10"x10" square.

If your image is less than 1000 pixals wide it would not be good to print it much larger than 4"x5". For a poster it needs to be well above 2000 pixels wide. Resample an image to enlarge it only makes it blurry. Data can be removed from and image but it can not be added. Always start larger than you need.

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Post by joegiampaoli » Sat Apr 14, 2007 3:51 am

something I forgot to mention and I think a lot of us do is we render much larger than needed, like 2X then we scale the final image 50% and it takes a lot of the grain away, but that is mostly for viewing on monitor, hope that tip helps for future renders, specially for presentations that will be viewed on monitors, TV etc. Obviuously for printing that would take a sh*tload of memory.
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Post by zsouthboy » Sat Apr 14, 2007 4:08 am

@joegiampaoli:

No need for supersampling of 2x when printing.
Image grain is always nicely masked somewhat by printing the image.
Same way that it masks "sharpness" of the original image, too. :)

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