Image resolution

R

RoystonB

Guest
Hi,

I’m quite new to Digital Photography and wondered if you could put me right on a couple of aspects. I have an Olympus 3030 zoom and it produces an image that is 28” by 22” at 72 dpi or ppi. That is over 3.3 million pixels.

1..….. Why are all images from digital cameras produced in 72 dpi?

As time goes on digital cameras will improve and produce images that are over 10 or even 20 million pixels in size. That will produce an image of something like 72” by 52”

2…… Are there moves afoot to increase the dpi to say 300 or more?

I am lucky enough to have a copy of Photoshop 4 that I use to manipulate my pictures.

3…… What is the correct way to resize my 28x22 @72dpi image to something that is printable, say, 11x8 @300dpi, to produce the best quality image?

I sometimes just go to Image, Image size, Document size, change the width and height and the resolution and hit OK.

Other times I feel that it should be done in two separate changes. I change the width 2 and the height and press OK and then return and change the resolution.

I always have it set on Bicubic and have the Constrain Proportions and Resample Image checked.


Many thanks in anticipation Royston :(
 

LV426

Administrator
Staff member
I'd suggest that the easiest way of resizing an image, whilst retaining its' total resolution (ie. without losing definition - subject to the abilities of the printer), is to load it into a DTP tool (eg Pageplus) and resize it (by dragging its handles) in there.

DPI is rather irrelevant, really. All it does is define at what size the image will appear by default ie. if you don't resize it. It makes no difference to the actual detail it contains.
 

[email protected]

Well-known Member
Originally posted by RoystonB


1..….. Why are all images from digital cameras produced in 72 dpi?

It may be just a coincidence but have you noticed that most computer monitors are also 72dpi?

So as you will probably viewing the photo on a normal monitor, if the dpi was higher, you would not see it.

Of course, when you come to printing, it's a different matter.
 

tomson

Active Member
When resizing an image its best not to resample as the quality suffers.
Other than that you're method is fine. Another way tho is to first set your crop tool to the printer paper's ration (eg 8:10), crop down the image, then adjust the resolution.

Oh, and dpi is really a printing term.
 

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