Pixels, dpi, photo deminsons & Screen display size.

[Guest]

I read that pixels and dots per inch determine the size and quality of
photos, but it's a total mystery to me why an 80Kb Jpg will display and fill
up my 17" Crt just a well as a 2Mb Tif.

Can some one tell me or suggest some reading that will enlighten a novice
about these relationships?

 

[John Inzer]

I read that pixels and dots per inch determine the size
and quality of photos, but it's a total mystery to me why
an 80Kb Jpg will display and fill up my 17" Crt just a
well as a 2Mb Tif.

Can some one tell me or suggest some reading that will
enlighten a novice about these relationships?

==================================
If (for example) you have your screen resolution
set to 1024 x 768...any image that size or larger
will fill your screen.

JPEG and TIFF are formats...the variation in
file size has to do with compression. IOW...
a 2 MB TIFF...resaved in the JPEG format
could be 80 KB even though the Pixel
Dimensions would still be the same.

Digital Image file Types Explained
http://tinyurl.com/7jyd

Resolution : Definition
http://tinyurl.com/5vf2b

--

John Inzer
MS Picture It! MVP
How to ask a newsgroup question:
http://support.microsoft.com/kb/555375

 

[Yves Alarie]

You can try this:
http://www.scantips.com/

Resolution on a screen is not that great, 72 or 96 pixels/inches.
To see the difference between your images, taken at different resolutions,
open them and then start zooming on the image. Deterioration will occur much
faster for an image taken at low resolution. Same thing when you print.
The problem here is that you are looking at file size. So you have a 80 Kb
jpg vs 2 MB Tif. These two file formats are different, JPG is a compressed
format which helps save space. To compare the resolution of these two files,
you need to look at the dimensions in pixels, not the file size in KB or MB.
To get this info quickly, just place your mouse pointer over the file name
and you will see the dimensions in pixels, or right click on the file, click
on Properties etc.
The dimensions in pixels will be something like 1500 x 1000 pixels. This
image, saved as JPG will be small (KB file size) but saved as Tif will be
large (MB file size).
With large files (in pixels) the software resize them(downsampling) to fill,
as best it can, your computer screen.