Scanning Calculator - inches to pixels

[nomads_05]

Is there a Scanning Calculator that will help you calculate the
variables to be used when you have the Input Size of the Photo, Film,
or Document in length (8.5 by 11 inches) and you want the output in
pixels?

For example how do you scan a magazine cover so that it will fill the
screen of various Apple monitors?

2560 x 1600 pixels
1920 x 1200 pixels
1680 x 1050 pixels
1280 x 854 pixels

 

[Paul Rubin]

For example how do you scan a magazine cover so that it will fill the
screen of various Apple monitors?

Scan it at 300 or 600 dpi and then scale the scanned image to the size
for whatever monitor.

 

[Philip Tobias]

Is there a Scanning Calculator that will help you calculate the
variables to be used when you have the Input Size of the Photo, Film,
or Document in length (8.5 by 11 inches) and you want the output in
pixels?

For example how do you scan a magazine cover so that it will fill the
screen of various Apple monitors?

2560 x 1600 pixels
1920 x 1200 pixels
1680 x 1050 pixels
1280 x 854 pixels

If you have Adobe Photoshop, you can use its Image Size dialog box
(Image > Image Size in Photoshop CS2) to do these calculations. For
instance, create a blank new document, then open the dialog box and play
around with the numbers.

Other image processing programs may have a similar image resizing dialog
box, which you can use to perform the calculations for you. So you may
have no need for a separate calculating program.

Good luck. ...pt

 

[Jack Rosier]

Is there a Scanning Calculator that will help you calculate the
variables to be used when you have the Input Size of the Photo, Film,
or Document in length (8.5 by 11 inches) and you want the output in
pixels?

For example how do you scan a magazine cover so that it will fill the
screen of various Apple monitors?

2560 x 1600 pixels
1920 x 1200 pixels
1680 x 1050 pixels
1280 x 854 pixels

check this out:
http://www.shortcourses.com/pixels/scanning.htm

 

[Bart van der Wolf]

Is there a Scanning Calculator that will help you calculate the
variables to be used when you have the Input Size of the Photo,
Film,
or Document in length (8.5 by 11 inches) and you want the output in
pixels?

For example how do you scan a magazine cover so that it will fill
the
screen of various Apple monitors?

2560 x 1600 pixels
1920 x 1200 pixels
1680 x 1050 pixels
1280 x 854 pixels

The math is relatively simple (hand calculator is fastest if the
scanning SW doesn't provide an input/output size dialog), but it
doesn't tell the whole story.

For the math part, if the goal is to represent the scan as e.g. 1600
pixels high and your document (assuming portrait orientation) is 11
inches high, that is 1600/11=145.45 pixels per inch scanning
resolution. You'll have to be careful with differences in aspect ratio
between the page/image and the screen, especially in landscape
orientation. You may want to scan for less than 1600 pixels if you use
a display program that doesn't allow full screen display.

For the non-math part, 145.45 ppi will get the screen size right, but
the quality of the scan will be less than optimal, especially when you
scan halftone prints (magazine covers). The scanner uses a sensor with
a certain native sampling density (e.g. 2400ppi), and
skips/interpolates/resamples for other size requirements. Scanning at
the scanner's native resolution will give the best quality result, but
it will also produce huge (!) files and the subsequent resampling can
introduce artifacts if not done right.

For a good compromise, it is often good enough to scan documents on a
flatbed scanner at 600ppi, and if the resulting image is too big (in
pixel dimensions) for the display, you apply some blur and downsample
to the screensize you need, and sharpen the final result. The amount
of blurring needed, depends on the amount of resizing and it is often
part of a "descreening" option of the scanner driver.

Bart

 

[CSM1]

Is there a Scanning Calculator that will help you calculate the
variables to be used when you have the Input Size of the Photo, Film,
or Document in length (8.5 by 11 inches) and you want the output in
pixels?

For example how do you scan a magazine cover so that it will fill the
screen of various Apple monitors?

2560 x 1600 pixels
1920 x 1200 pixels
1680 x 1050 pixels
1280 x 854 pixels

The easiest calculator to use is:
http://www.scantips.com/calc.html

 

[nomads_05]

Thank you,
Paul and Bart's replies about a scanning calculations, has been very
helpful. Philip, Adobe Photoshop is magnificent. It lets you put in
any variable and solve for the missing input.

Someone far away, in another land, will be running scans for me. These
will be saved to CD so size does not matter. I am thinking about
"Portable Network Graphics," (.png). What do you think?

Should I have him shoot it in the scanners, natural/optical resolution,
and I just take it from there?

So Photoshop it is for the scanning calculations, however, for those
not fortunate enough to have Adobe, what Paul has posted needs some
comment. Although other sources agree, "Scanning an image for the
screen is the same as scanning one for printing except the output is
usually specified in pixels, not inches." Scanning an Image for
Screen Display at http://www.shortcourses.com/pixels/scanning.htm also
say's "images are usually scanned at 72pp for screen display."
This is simply not true and flies in the face of what we learn from
Wayne Fulton's visual examples at the web site posted by CSM1.
Shortcourses also says the screen's resolution is on average 72 dpi.
This appears to be pure bull. You do not measure pixels in inches. I
am sorry but it looks like this writer has a problem explaining what
he, thinks he means.

1 Enter the width in inches of the image to be scanned.
2 Enter the depth or height of the image to be scanned.
3 Enter the screen's resolution in dots per inch (dpi). This is
normally 72 dpi on average.
4 Enter the desired width of the image in pixels.
5 The vertical size of the image is calculated by dividing its width on
line 4, by the ratio of the original's width to height; calculate by
dividing line 1 by line 2.

Does this make any sense to you?

www.scantips.com/no72dpi.html site is very informative, but it does
NOT have a calculation from inches to pixels, which was the question.
Fulton's calculator would be much more useful if you could pose
questions for any missing variable, and not just linearly. All you can
do with that thing is to print. I do not want to print. The question
involves the natural flow of the universe. Moving from hard to soft,
yang to yin, print (inches) to screen (pixels.) In essence moving from
the past into the future.

Much Mahalo..

 

[CSM1]

Thank you,
Paul and Bart's replies about a scanning calculations, has been very
helpful. Philip, Adobe Photoshop is magnificent. It lets you put in
any variable and solve for the missing input.

Someone far away, in another land, will be running scans for me. These
will be saved to CD so size does not matter. I am thinking about
"Portable Network Graphics," (.png). What do you think?

Tiff is more portable and widely supported and lossless.
If you do not mind a lossy format, then High Quality Jpeg is the way to go.

Image formats:
http://www.scantips.com/basics09.html

Should I have him shoot it in the scanners, natural/optical resolution,
and I just take it from there?

So Photoshop it is for the scanning calculations, however, for those
not fortunate enough to have Adobe, what Paul has posted needs some
comment. Although other sources agree, "Scanning an image for the
screen is the same as scanning one for printing except the output is
usually specified in pixels, not inches." Scanning an Image for
Screen Display at http://www.shortcourses.com/pixels/scanning.htm also
say's "images are usually scanned at 72pp for screen display."
This is simply not true and flies in the face of what we learn from
Wayne Fulton's visual examples at the web site posted by CSM1.
Shortcourses also says the screen's resolution is on average 72 dpi.
This appears to be pure bull. You do not measure pixels in inches. I
am sorry but it looks like this writer has a problem explaining what
he, thinks he means.

1 Enter the width in inches of the image to be scanned.
2 Enter the depth or height of the image to be scanned.
3 Enter the screen's resolution in dots per inch (dpi). This is
normally 72 dpi on average.
4 Enter the desired width of the image in pixels.
5 The vertical size of the image is calculated by dividing its width on
line 4, by the ratio of the original's width to height; calculate by
dividing line 1 by line 2.

Does this make any sense to you?

www.scantips.com/no72dpi.html site is very informative, but it does
NOT have a calculation from inches to pixels, which was the question.
Fulton's calculator would be much more useful if you could pose
questions for any missing variable, and not just linearly. All you can
do with that thing is to print. I do not want to print. The question
involves the natural flow of the universe. Moving from hard to soft,
yang to yin, print (inches) to screen (pixels.) In essence moving from
the past into the future.

A calculation from Pixels to Inches or Inches to Pixels requires the DPI
(Dots Per Inch) or PPI (Pixels Per Inch) that you are going to use for the
scan.

You can scan a 8.5 x 11 magazine and make it fit any screen size by Resizing
and Cropping. A magazine should be descreened with the scanner descreen
function at scan time.
http://www.scantips.com/basics06.html


The quality of the image depends on the DPI the document was scanned at.
For a Paper product, it has been shown that 300 DPI to 600 DPI is about all
the information contained in a paper document or photograph. (Not true for
film).

Since you are not the person making the scan, I would ask for 300 DPI at a
minimum. You can resize the image in Photoshop, but you can not put back
what was loss in the scan.

Now for the size of the image in pixels if you scan that 8.5" X 11" document
at 300 DPI.

The math: DPI or PPI can be used (they are almost the same thing).
(Inches) times (Dots Per Inch) = Pixels.
(Pixels) divided by (Dots Per Inch) = Inches.

(Pixels) divided by (Inches) = Dots Per Inch (or in this case PPI).

8.5 times 300 = 2550 pixels
11 times 300 = 3300 pixels
So you get 2550 X 3300 pixels from a 8.5" x 11" magazine when scanned at 300
DPI.

If you scan at 600 DPI (this is over kill).
8.5 * 600 = 5100
11 * 600 = 6600
At 600 DPI you get 5100 x 6600 Pixels.

To fit any of your screen sizes takes some resizing and cropping of the
image.
Adobe Photoshop is very good at that job!

Personally, I very seldom scan a 8.5 x 11 document at more than 150 DPI.
I make copies (scan/print) at 150 DPI. A fax is 200 DPI.

Much Mahalo..