How much dpi do you put in a processed pic?


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prodigic

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Jan 19, 2008
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#1
As per topic, I usually shoot in RAW and when I batch process in Lightroom, there's this option to input your picture resolution to how many dpi (dots per inch) to convert the pix into JPEG.

Just wondering, how much dpi do u guys input? Does it make a big difference when I put it at 300dpi or 1024dpi except that it increases the size of jpg file?

Need some help in this. Tks in advance!

:)
 

catchlights

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Sep 27, 2004
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www.foto-u.com
#5
As per topic, I usually shoot in RAW and when I batch process in Lightroom, there's this option to input your picture resolution to how many dpi (dots per inch) to convert the pix into JPEG.

Just wondering, how much dpi do u guys input? Does it make a big difference when I put it at 300dpi or 1024dpi except that it increases the size of jpg file?

Need some help in this. Tks in advance!

:)
DPI is only relevance to the size of your final outputs, if unsure just leave it as original dimension. eg XXXXpixel by XXXXpixel
 

tanhb

Senior Member
Mar 21, 2004
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#6
72dpi for web posting.
300dpi for printing.

You only see the different during printing. You would not see any different when viewing on screen. 72dpi or 300dpi or 1000dpi all look the same on your computer screen.

......except that it increases the size of jpg file?
:)
Really? Never take note whether it increase file size, and I don't think it should. It's just a setting for your print job only.
 

Michael

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Apr 5, 2005
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www.pbase.com
#7
As per topic, I usually shoot in RAW and when I batch process in Lightroom, there's this option to input your picture resolution to how many dpi (dots per inch) to convert the pix into JPEG.

Just wondering, how much dpi do u guys input? Does it make a big difference when I put it at 300dpi or 1024dpi except that it increases the size of jpg file?

Need some help in this. Tks in advance!

:)
dpi has no relevance whatsoever UNLESS your software links the dpi with the dimension of the photo. With dimension i mean cm or inch, in that case if you change the dpi the software changes the total pixel count.
 

prodigic

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Jan 19, 2008
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#8
Oh ok guys.. thank you for your explanations. So only when I want to print, then i'll bump the dpi.. unless just leave it as it is.

Thanks! ;)
 

chisiang

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Oct 3, 2004
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#9
DPI has impact on the file size.

For FA, your dimension must be finalised, as in cm, inches or mm. If you tell your printer you want to print in pixel he will ask you go fly kite. So if you set 300 dpi for a wall mural or poster, you're gonna end up with 1GB of FA, but not before your computer takes ages to save the file and hang :bsmilie:

If you tell your printer to fit your photo to the dimension that you wanted, he will charge you fee for artwork.

For Magazine: 300
For Anything that exceeds A4: usually 150 dpi
For Wall mural/big poster: 100~150 dpi

For FA, usually can save in EPS or like SPH PDF (but they got a guideline for color management and others to follow)

If only photographic mural/poster, JPG 80% will do otherwise they will tell you the format.

:)
 

V

vince123123

Guest
#10
DPI has no impact on file size for the same pixels that you have. DPI is merely a set of instructions that correlate your actual pixels in your RAW file, and translates that to the number of dots it prints out into a printer.

For example, you have a 1000 x 1000 RAW photo. If you set it to 100dpi, it will print to a size of 10inches x 10inches. If you set it to 250dpi, the same RAW file will print to 4 inches by 4 inches.

If you know that you need to print 10inches x 10 inches, and you know you want it to be 300dpi, you will then need to upsize your RAW file from 1000pixels x 1000pixels to 3000 x 3000, if not you will not be able to do what you want.

I repeat, DPI is just a set of instructions embedded in the digital file. It does not affect the file size. It only affects the file size if you are going to constraint the printed dimensions (ie you know you want 10inches printed output, making the file 300dpi will result in the software upscaling to 3000 x 3000 pixels in order to fit that 10inches prinout at 300dpi).
 

chisiang

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#11
tell me what is the file size if I want to print a mural measuring 7000mm x 2500mm @ 100 dpi? If you say 300 dpi, what file size would that be?
 

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V

vince123123

Guest
#12
As I said before, if the print size is the same, the file size will increase because you are adding more pixels by forcing the file to upscale in order to match your print size at that DPI. There are three sides to the triangle, print size, DPI and pixel dimensions.

That is because you are taking a print-centric approach.

In the TS's case, he asked how much DPI to put in a processed pic. This means he is asking from a digital file centric approach. For his digital file, whether he puts 300dpi or 100dpi in Photoshop, the file size remains the same; so long as he doesn't increase the print size in photoshop.

Anyway, the way you ask the question is overly confrontational. Can I ask you if you even know the answer to your own questions? I understand your point, but the way you put it could be clearer.

If I were to adopt your approach, I'll simply ask you this rather than explain everything above:

"Can you tell me what is the file size if I have a digital file with 10000 pixels x 10000 pixels and I set it to 100dpi, and I then use the same pixel dimensions and now set it to 300dpi?"

tell me what is the file size if I want to print a mural measuring 7000mm x 2500mm @ 100 dpi? If you say 300 dpi, what file size would that be?
 

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chisiang

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#13
As I said before, if the print size is the same, the file size will increase because you are adding more pixels by forcing the file to upscale in order to match your print size at that DPI. There are three sides to the triangle, print size, DPI and pixel dimensions.

That is because you are taking a print-centric approach.

In the TS's case, he asked how much DPI to put in a processed pic. This means he is asking from a digital file centric approach. For his digital file, whether he puts 300dpi or 100dpi in Photoshop, the file size remains the same; so long as he doesn't increase the print size in photoshop.

Anyway, the way you ask the question is overly confrontational. Can I ask you if you even know the answer to your own questions? I understand your point, but the way you put it could be clearer.

If I were to adopt your approach, I'll simply ask you this rather than explain everything above:

"Can you tell me what is the file size if I have a digital file with 10000 pixels x 10000 pixels and I set it to 100dpi, and I then use the same pixel dimensions and now set it to 300dpi?"
my bad. sorry if I offended you in any way. :)
 

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