Does Dpi even matter?


Jun 19, 2011
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#1
Hi seniors,

I've try reading up about DPI but apparently everyone have a different say. Does Dpi matter when we are doing printing? If not, how does DPI affect our work? Currently I'm using D7000 and the DPI I'm getting is 300, is there anyway to increase the DPI?

Thank you
 

#4
Hi seniors,

I've try reading up about DPI but apparently everyone have a different say. Does Dpi matter when we are doing printing? If not, how does DPI affect our work? Currently I'm using D7000 and the DPI I'm getting is 300, is there anyway to increase the DPI?

Thank you
According to what others are saying, 200DPI are more than gd enough for gd prints :) How large are u printing anw?

http://forums.dpreview.com/forums/readflat.asp?forum=1034&message=34749823&changemode=1
 

catchlights

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#5
To be exact, you don't get 300ppi from your D7000, you use 300ppi to know what size of print you can make, and make sure you have enough pixel size.
 

ZerocoolAstra

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#6
Hi seniors,

I've try reading up about DPI but apparently everyone have a different say. Does Dpi matter when we are doing printing? If not, how does DPI affect our work? Currently I'm using D7000 and the DPI I'm getting is 300, is there anyway to increase the DPI?

Thank you
D7000 gives you the largest possible image size of 4928 x 3264 pixels. This is the critical number.
If you want to print at 300 dpi (dots per inch), the largest print size achievable is 4982/300 x 3264/300

which is 16" x 11".

Therefore you go from image size (in pixels), then you choose the printing resolution you require (eg 300 or 200 dpi), which gives you the final print size :)

* take note that there is a limit to how fine a detail the human eye can resolve/discern as well... :)
 

David Kwok

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#7
250dpi is good for printing where you viewing distance is at least an arms length to 2m away.In fact, dpi doesn't matters to the size. 250 dpi is the same whether it is a billboard or a 4R.It only matters when you include in how far you look at picture from. For a billboard, unless you are viewing it from 1m away, I say even 72dpi works.
 

Cowseye

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#8
Erm, taking D7000 with 300dpi printing at the calculated 16" by 11", is that the biggest, finest and shortest viewing distance picture this camera can produce?

Btw, thanks ZCA. I've been looking for what u replied abt the resolution vs. dpi info for a few weeks le. Thanks. :)
 

ZerocoolAstra

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#9
Cowseye said:
Erm, taking D7000 with 300dpi printing at the calculated 16" by 11", is that the biggest, finest and shortest viewing distance picture this camera can produce?

Btw, thanks ZCA. I've been looking for what u replied abt the resolution vs. dpi info for a few weeks le. Thanks. :)
No prob.

Btw I do feel that 300dpi is a bit overkill even when viewing quite close up.
The larger the intended print size, the greater the viewing distance as well... so, required DPI goes down once more.
 

Cowseye

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#10
ZerocoolAstra said:
No prob.

Btw I do feel that 300dpi is a bit overkill even when viewing quite close up.
The larger the intended print size, the greater the viewing distance as well... so, required DPI goes down once more.
Is there a guideline by plotting dpi against distance of view?
 

Cowseye

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#12
ziploc said:
Thanks ziploc :)
Very informative but very technical. I can't grasp everything but I get the rough idea. The greater the viewing distance, the lesser ppi needed. However, as size of print gets larger while distance of view gets shorter, the more ppi u need to maintain a sharp image. Am I right?
 

David Kwok

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#13
The larger the print, the further an audience will be expected to stand away from image. Then it is back to

1/((distance x 0.000291) / 2)

How much DPI do you feel the big screen at shaw centre is ?

Thanks ziploc :)
Very informative but very technical. I can't grasp everything but I get the rough idea. The greater the viewing distance, the lesser ppi needed. However, as size of print gets larger while distance of view gets shorter, the more ppi u need to maintain a sharp image. Am I right?
 

ZerocoolAstra

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#14
David Kwok said:
The larger the print, the further an audience will be expected to stand away from image. Then it is back to

1/((distance x 0.000291) / 2)

How much DPI do you feel the big screen at shaw centre is ?
... or the one at Suntec? ;)
 

Cowseye

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#15
The larger the print, the further an audience will be expected to stand away from image. Then it is back to

1/((distance x 0.000291) / 2)

How much DPI do you feel the big screen at shaw centre is ?
I'm refering to those mobile stand poster which is about 2 x A1 (or A0) I think? Though good enough to view from 5 metres away but ppl tend to view them while walking as close as 1m or less.
 

David Kwok

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#16
If you intent for the audience to stand close, then you will need to use that as your gauge. Typically I say 2 arms length for mobile stand poster which is roughly 3/4 the height of a person ? Are you referring to those poster ? At 24 inches =~ 60cm, it will be roughly 1 arms length ( found it nominally at 28inchs). So 2 arms length will be roughly 48inchs ?
Hence my gauge is 150dpi is more than enough. If you want it safer, go for 200dpi. That's quite enough.

If you have a chance to sample it, perhaps you might wanna print out a 200dpi sample and see how it is ? You have not indicated if the poster is full photograph or include design such as big bold text. If text is involved, I say you hit for 300dpi, so that the text vectors will be crispy. Tone images are less affected by lack of dpi which can be easily boost using interpolation.

I'm refering to those mobile stand poster which is about 2 x A1 (or A0) I think? Though good enough to view from 5 metres away but ppl tend to view them while walking as close as 1m or less.
 

catchlights

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#17
I'm refering to those mobile stand poster which is about 2 x A1 (or A0) I think? Though good enough to view from 5 metres away but ppl tend to view them while walking as close as 1m or less.
viewing so close you won't able to see the whole picture, anyway, they might be reading the "fine print", looking for the any discount offered, nobody really care much about the photos, unlike photographers pixel peep all the time.
 

Cowseye

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#18
viewing so close you won't able to see the whole picture, anyway, they might be reading the "fine print", looking for the any discount offered, nobody really care much about the photos, unlike photographers pixel peep all the time.
haha, they probably won't.
However, there are those who use low res photos as part of the poster along with "fine prints". The photos is extremely, badly pixelated... It may not be what people are looking at but can be quite distracting in my opinion.
 

Cowseye

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#19
If you intent for the audience to stand close, then you will need to use that as your gauge. Typically I say 2 arms length for mobile stand poster which is roughly 3/4 the height of a person ? Are you referring to those poster ? At 24 inches =~ 60cm, it will be roughly 1 arms length ( found it nominally at 28inchs). So 2 arms length will be roughly 48inchs ?
Hence my gauge is 150dpi is more than enough. If you want it safer, go for 200dpi. That's quite enough.

If you have a chance to sample it, perhaps you might wanna print out a 200dpi sample and see how it is ? You have not indicated if the poster is full photograph or include design such as big bold text. If text is involved, I say you hit for 300dpi, so that the text vectors will be crispy. Tone images are less affected by lack of dpi which can be easily boost using interpolation.
Ah, well. It's more for those mobile road show (e.g.: credit card road show) and the content could be a mixed of photos with words as advertisements. Of course it's meant for people to view from a distance but also likely for others to stand (or sit) close to the banner/poster. Not yet having to tap into this line of work, but I thought it would be good to know.
 

David Kwok

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#20
Yes I understand what you meant by the pixelated display, I have came across them sometimes. IMHO that is plain low quality work, but then again, most of these fellas probably ain't interested in the artwork and more about sales. The displays just serve as decoration or secondary information. Their first hand information is still face to face talk with the customers.

When you now mentioned it's a mixture of text and photographers, the situation changes. I find myself not particularly affected by soft images, but rather soft text. Because text are vectors and images are raster, I tend to be more relaxed on images quality as I know with such large poster, you can't expect images to be sharp unless the images used are dedicated for that size of poster and hence the photographer would have tried his/her best to produce images that suit the usage without cropping and then interpolate enlarge.

I suppose the way to produce such poster is using tools like Adobe InDesign, successor to previously PageMaker. You placed your images and text together. When you send such a file or its output in TIFF to the printing house, they will advice like 250dpi to 300dpi, but that doesn't mean your image has to be that fine. Your text is better to be at 300dpi, that means the whole file (if it's a raster), will need to be at 300dpi. That's the target dpi and also the container dpi. Images inside this container can come from source of 150dpi and resample to 300dpi. Here the images will look softer, but with good interpolation algorithm, it can look smooth depending on how much it interpolate and whether the source image contains largely graphical contents or tone contents.

Based on the size you mentioned for mobile poster, I won't be surprised a 10MP camera can do the job just fine. Visually nice images don't just comes from high pixel count. Noises in the image also plays important factor. If your image is largely noise free, it looks good when enlarge, if not the noise will also enlarge at the same time. I say human perception feel disgusted with chromatic noise versus luminosity noise. A good NR software will help you to achieve good output without going for high DPI.

Ah, well. It's more for those mobile road show (e.g.: credit card road show) and the content could be a mixed of photos with words as advertisements. Of course it's meant for people to view from a distance but also likely for others to stand (or sit) close to the banner/poster. Not yet having to tap into this line of work, but I thought it would be good to know.
 

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