Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
04-21-2009, 02:58 PM   #31
Veteran Member
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by graphicgr8s Quote
How big is a pixel?
How big do you want it to be?

04-21-2009, 03:53 PM   #32
Damn Brit
Guest




QuoteOriginally posted by Marc Sabatella Quote
How big do you want it to be?
Well there are physical limitations at the moment Marc, depending on the sensor used. But obviously technology will push those limitations over time. And the shape of them is important too. I think the largest a pixel can be is going to be a little smaller than the largest sensor available.
04-21-2009, 03:57 PM   #33
Veteran Member
jeffkrol's Avatar

Join Date: Sep 2006
Location: Wisconsin USA
Photos: Gallery
Posts: 8,434
1 inch = 18 pixels...

04-21-2009, 07:10 PM   #34
graphicgr8s
Guest




QuoteOriginally posted by Marc Sabatella Quote
How big do you want it to be?
1/300"

10char

04-21-2009, 07:51 PM   #35
Veteran Member




Join Date: Mar 2007
Location: Toronto (for now)
Posts: 1,746
The usual people spouting the usual misinformation. The DPI figure DOES count in this instance. If you provide a 300 DPI file that is set to say 4 x 6 inches then they can print it. If you provide a 50 DPI file at 4x6 inches then they are gonna struggle.

Some here will say that this is essentially just re-sizing and there was no need to change the DPI, just change the image size. This is correct to a point but then you're sending a very small image to a client and they will twig as to what you are doing. Send a large photo with low DPI and most clients will have NFI why it prints badly.
04-21-2009, 08:25 PM   #36
graphicgr8s
Guest




QuoteOriginally posted by Marc Sabatella Quote
Changing the *actual* dpi does this. Changing the meaningless number stored in the EXIF does nothing of the sort. In fact, it does nothing of *any* sprt - it does nothing at all. It's as relevant to the discussion as changing the file-modified date. That won't *really* make the picture go back (or forward) in time any more than chanigng the EXIF resolution figure will change the *actual* resolution of any printed image. The actual resolution is number of pixels divided by size in inches - very literally, pixels per inch. Nonumber stored in any EXIF will ever change this. The only way to change to resolution of an image to be printed at a given size is to actually change the number of pixels. You can't divide 3000 by 10 and ever get anything but 300. If you want something other than a 300dpi image in a 10" print, you're going to need something other that 3000 pixels.
If it makes you feel better call it ppi instead of dpi. It is still 1/3 of the equation. You can say it doesn't matter but it is still part of the equation. Semantics is all.
04-21-2009, 09:28 PM   #37
Veteran Member
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by Alfisti Quote
The usual people spouting the usual misinformation. The DPI figure DOES count in this instance. If you provide a 300 DPI file that is set to say 4 x 6 inches then they can print it. If you provide a 50 DPI file at 4x6 inches then they are gonna struggle.
That's looking a it backwards. A image doesn't have dpi nor does it have a size in inches. All it has are pixels. The other two parameters - size and dpi - are determined when you go to print, and are not - cannot *possibly* be - attributes of the images. An images has a certain number number of pixels. It does not *have* a resolution in dpi. That's not misinformation, it's the nature of digital imaging.

So sure, you could say you have an image that is "a 300 dpi file that is set to 4x6 inches" - but that's an extremely roundabout and technically inaccurate way of saying it has 1200x1800 pixels.
04-21-2009, 09:32 PM   #38
Pentaxian
Wheatfield's Avatar

Join Date: Apr 2008
Location: The wheatfields of Canada
Posts: 12,510
QuoteOriginally posted by Alfisti Quote
The usual people spouting the usual misinformation. The DPI figure DOES count in this instance. If you provide a 300 DPI file that is set to say 4 x 6 inches then they can print it. If you provide a 50 DPI file at 4x6 inches then they are gonna struggle.

Some here will say that this is essentially just re-sizing and there was no need to change the DPI, just change the image size. This is correct to a point but then you're sending a very small image to a client and they will twig as to what you are doing. Send a large photo with low DPI and most clients will have NFI why it prints badly.
So far, I haven't read anything on this thread that would count as misinformation. Perhaps you'd care to point out who you are talking about and what information you think is incorrect rather than blathering.


Last edited by Wheatfield; 04-21-2009 at 10:07 PM. Reason: So Gary wouldn't have to brig me again.
04-21-2009, 09:34 PM   #39
Veteran Member
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by graphicgr8s Quote
If it makes you feel better call it ppi instead of dpi. It is still 1/3 of the equation. You can say it doesn't matter but it is still part of the equation. Semantics is all.
Yes, the *real* resolution of the printed image is part of the equation. The number stored in the EXIF is *not*.

As I said above, an image does not have a resolution in dpi (or ppi). It does not, cannot, will not ever. That's a meaningless as saying a car has a speed in MPH. The car doesn't have a speed until you drive it, and the image doesn't have a resolution in dpi or ppi until you print it. Saying that file X is 300dpi and file Y is 72dpi is completely and utter nonsense - no file has a resolution in dpi, because a pixel doesn't have a size until you print it, and then the size of the pixel will be a size of print / #pixels.

One of these days I'll think of a clear way to explain this that will finally convince people. Today, apparently, is still not that day.
04-21-2009, 10:09 PM   #40
Pentaxian
Wheatfield's Avatar

Join Date: Apr 2008
Location: The wheatfields of Canada
Posts: 12,510
QuoteOriginally posted by Marc Sabatella Quote
Yes, the *real* resolution of the printed image is part of the equation. The number stored in the EXIF is *not*.

As I said above, an image does not have a resolution in dpi (or ppi). It does not, cannot, will not ever. That's a meaningless as saying a car has a speed in MPH. The car doesn't have a speed until you drive it, and the image doesn't have a resolution in dpi or ppi until you print it. Saying that file X is 300dpi and file Y is 72dpi is completely and utter nonsense - no file has a resolution in dpi, because a pixel doesn't have a size until you print it, and then the size of the pixel will be a size of print / #pixels.

One of these days I'll think of a clear way to explain this that will finally convince people. Today, apparently, is still not that day.
I get it, if that makes you happy.
04-21-2009, 10:51 PM   #41
Veteran Member




Join Date: Apr 2007
Location: Melb. Aust
Posts: 841
QuoteOriginally posted by Wheatfield Quote
I get it, if that makes you happy.
me too!
04-22-2009, 12:01 AM   #42
Senior Member




Join Date: May 2008
Location: stockholm
Photos: Albums
Posts: 111
QuoteOriginally posted by graphicgr8s Quote
If it makes you feel better call it ppi instead of dpi. It is still 1/3 of the equation. You can say it doesn't matter but it is still part of the equation. Semantics is all.
I dont agree, X*Y in pixels is the only part of the equation. Then you can use this information to make it understandable in the physical world.

Except for layout software, the computer will not display images with different dpi tags in different sizes. Simple as that...
And if you print them, the first thing you do is to make clear that it fits the paper its going to be printed on.
04-22-2009, 06:17 AM   #43
Veteran Member
jeffkrol's Avatar

Join Date: Sep 2006
Location: Wisconsin USA
Photos: Gallery
Posts: 8,434
Splitting a large hair

QuoteOriginally posted by Marc Sabatella Quote
That's looking a it backwards. A image doesn't have dpi nor does it have a size in inches. All it has are pixels. The other two parameters - size and dpi - are determined when you go to print, and are not - cannot *possibly* be - attributes of the images. An images has a certain number number of pixels. It does not *have* a resolution in dpi. That's not misinformation, it's the nature of digital imaging.

So sure, you could say you have an image that is "a 300 dpi file that is set to 4x6 inches" - but that's an extremely roundabout and technically inaccurate way of saying it has 1200x1800 pixels.
Actually it seems to me that an image has a starting size ie 14mp's contained in a 24x16mm frame. So each "pixel" starts off at 6 (2, 5, 9 ect)microns (forgive the sweeping generalities and pretend the software has interpolated each sensel into one "color"). From there you enlarge (shrink) or multiply (divide) to "FIT" the container of your choice at a density of your choice...
As long as uprezing (downrezing) isn't done the "tag" is meaningless until you give it meaning.....
of course an image printed at "native" size would be exactly the size of the sensor minus dead space at an extremely high "ppi" (198 pixels per mm or 5029 ppi)
Roughly... I think.......
Old printer stats.....
Canon's new print head features Micro-Nozzles capable of delivering consistent 2pl droplets with ultimate dot placement and giving a true resolution of 4800 x 1200 dpi. At 10 microns in diameter, the individual nozzles are about 40% smaller than the closest competitor's
04-22-2009, 06:25 AM   #44
Veteran Member




Join Date: Mar 2008
Location: CT / NY
Photos: Gallery
Posts: 822
Original Poster
QuoteOriginally posted by Marc Sabatella Quote
That's looking a it backwards. A image doesn't have dpi nor does it have a size in inches. All it has are pixels. The other two parameters - size and dpi - are determined when you go to print, and are not - cannot *possibly* be - attributes of the images. An images has a certain number number of pixels. It does not *have* a resolution in dpi. That's not misinformation, it's the nature of digital imaging.
QuoteOriginally posted by Alfisti Quote
The usual people spouting the usual misinformation. The DPI figure DOES count in this instance. If you provide a 300 DPI file that is set to say 4 x 6 inches then they can print it. If you provide a 50 DPI file at 4x6 inches then they are gonna struggle.


Obviously I have no idea what the final word is!


The thing is, why when I am exporting in LightRoom I have the option to choose DPI and canvas size at the same time, if apparently it is redundant?
04-22-2009, 06:57 AM   #45
Veteran Member
jeffkrol's Avatar

Join Date: Sep 2006
Location: Wisconsin USA
Photos: Gallery
Posts: 8,434
QuoteOriginally posted by BBear Quote
The thing is, why when I am exporting in LightRoom I have the option to choose DPI and canvas size at the same time, if apparently it is redundant?
No , not correct..... Choosing dpi and allowing the software to create a container to fit is non-destructive. Choosing both will modify (unless lucky ) the file itself...
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
dpi, photography, photos, photoshop, print
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Traditional print vs scan & print rodneysan Pentax Medium Format 8 05-06-2010 03:33 PM
Your most basic PP method? KierraElizabeth Digital Processing, Software, and Printing 31 08-03-2009 11:21 PM
A New Method... Buddha Jones Photographic Technique 29 05-05-2009 06:49 PM
learned a new method of sharpening (PS) volosong Digital Processing, Software, and Printing 4 05-04-2007 12:07 PM
Another Workflow Method... benjikan Digital Processing, Software, and Printing 0 03-16-2007 02:37 PM



All times are GMT -7. The time now is 08:56 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top