Some of this is above my head but I figured it is good
info to pass along. You probably cant see the chart,
however if you click on the URL you should be able to
see it.
http://www.design21 5.com/toolbox/ megapixels. php
http://www.design21 5.com/toolbox/ print_guide. php
Megapixels Chart
v1.0, 2005.12.26
Each colored box represents a certain number of
megapixels. The numbers along the top and left side
are print dimensions in inches at 300ppi (pixels per
inch). Most books and magazines require 300ppi for
photo quality. For example, the chart shows that you
can make a 5" x 7" photo quality print from a 3
megapixel camera.
inches @ 300ppi (numbers inside colored boxes are
megapixels)
Notice that as the print size doubles, the megapixels
required increases geometrically. You can make nice 8"
x 10" prints with a 6 or 8 megapixel camera, but to
make a true photo quality 16" x 20" print, you need
between 24 and 30 megapixels. Don't be fooled by
manufacturers' claims that say you can make 16" x 20"
prints from an 8 megapixel camera. While you certainly
can make a print that size, it will not be true photo
quality.
Here's why:
A megapixel is 1 million pixels. It's an area
measurement like square feet.
A typical 8 megapixel camera produces images that are
3266 x 2450* pixels.
If you multiply 3266 by 2450, you get 8,001,700 or 8
million pixels.
To find the largest photo quality image you can print,
simply divide each dimension by 300:
3266 / 300 = 10.89 inches
2450 / 300 = 8.17 inches
If you are not publishing your images in a book or
magazine, and you're just making prints for yourself
or your friends, you can "cheat". Good quality inkjet
printers can make a nice looking print at 250 or
200ppi. At 200ppi, the maximum print size becomes:
3266 / 200 = 16.33 inches
2450 / 200 = 12.25 inches
If you know how to use image editing software like
Photoshop, you can "cheat" even more by increasing the
image size, and even doubling the number of pixels in
the image. The quality of the camera and lense becomes
more important at this point bacause any loss of
detail or sharpness is magnified. If an image is
enlarged too much in this manner, it will look "fuzzy"
or "pixelated".
Megapixels vs. Maximum Print Size Chart
Megapixels Pixel Resolution* Print Size @ 300ppi Print
size @ 200ppi Print size @ 150ppi**
3 2048 x 1536 6.82" x 5.12" 10.24" x 7.68" 13.65" x
10.24"
4 2464 x 1632 8.21" x 5.44" 12.32" x 8.16" 16.42" x
10.88"
6 3008 x 2000 10.02" x 6.67" 15.04" x 10.00" 20.05" x
13.34"
8 3264 x 2448 10.88" x 8.16" 16.32" x 12.24" 21.76" x
16.32"
10 3872 x 2592 12.91" x 8.64" 19.36" x 12.96" 25.81" x
17.28"
12 4290 x 2800 14.30" x 9.34" 21.45" x 14.00" 28.60" x
18.67"
16 4920 x 3264 16.40" x 10.88" 24.60" x 16.32" 32.80"
x 21.76"
35mm film, scanned 5380 x 3620 17.93" x 12.06" 26.90"
x 18.10" 35.87" x 24.13"
*Typical Resolution. Actual pixel dimensions vary from
camera to camera.
**At 150ppi, printed images will have visible pixels
and details will look "fuzzy".
For an explanation of "pixels per inch" vs. "dots per
inch" and why you need 300ppi for true photo quality,
see our Printing Guide.
************ ********* ********* ********* ********
Photography Printing Guide
v1.0, 2005.12.27
dpi is NOT THE SAME as ppi !!
Even though "dots per inch" (dpi) and "pixels per
inch" (ppi) are used interchangeably by many, they are
not the same thing. Traditional printing methods use
patterns of dots to render photographic images on a
printed page. While pixels on a monitor are square and
in contact with the adjacent pixels, printed dots have
space between them to make white, or no space between
them to make black. Color photographs are printed
using four inks, Cyan, Magenta, Yellow, and Black
(CMYK), and four separate dot patterns, one for each
ink. Dots per inch (dpi) refers to printed dots and
the space between them, while pixels per inch (ppi)
refers to the square pixels in a digital image. Keep
in mind that many companies will ask for images at
300dpi when they really mean 300ppi.
Why do I need 300ppi for a "photo quality" image?
First, some background information is necessary. A
digital image is what it is. It is however many pixels
wide by however many pixels tall. If you divide each
dimension by 300, you will have the size of the image
at 300ppi. Now think about 300 pixels in an inch of
space. Each pixel could be black, white, or any other
color, but they are all next to each other with no
spaces between them. When a digital image is prepared
for reproduction on a printing press, pixels are
converted to dots. Dots have spaces between them. 300
pixels become 150 dots and spaces, so 300ppi becomes
roughly 150dpi. 150dpi is the accepted standard for
printing photographic quality images.
Printers usually refer to the number of rows or lines
per inch (LPI). 150 lines per inch is simply 150 rows
of 150 dots per inch. 150 LPI and 133 LPI have long
been the established standards for the best quality
reproduction of photographs in books and magazines.
Newspapers traditionally use 85 LPI for photographs
and detail is lost because the dots are plainly
visible.
Viewing distance changes everything!
Everything is relative to viewing distance. 150dpi (or
300ppi) is accepted as photo quality because the
average person cannot see the "dots" at a few inches
away. A real photograph made from film in a darkroom
has no dots or pixels and therefore is the standard by
which "photo quality" is judged. When you move the
viewer further away from the printed material, lower
dpi is acceptable. A huge billboard might be printed
at only 40dpi but no one notices because everyone is
50 yards away from it.
I always see "72dpi". Where is that used?
72dpi should really be 72ppi because most likely, it
has nothing to do with printing. Most of the time,
72dpi refers to output on a computer monitor. A 72
pixel by 72 pixel image should take up about one inch
of space on the screen. This of course depends on the
size of the monitor and what resolution it is set to.
When creating images for web sites, we've found it's
best to determine what screen resolutions will be used
most often by that site's visitors, instead of
thinking about inches at all.
Megapixels vs. Maximum Print Size Chart
Megapixels Pixel Resolution* Print Size @ 300ppi Print
size @ 200ppi Print size @ 150ppi**
3 2048 x 1536 6.82" x 5.12" 10.24" x 7.68" 13.65" x
10.24"
4 2464 x 1632 8.21" x 5.44" 12.32" x 8.16" 16.42" x
10.88"
6 3008 x 2000 10.02" x 6.67" 15.04" x 10.00" 20.05" x
13.34"
8 3264 x 2448 10.88" x 8.16" 16.32" x 12.24" 21.76" x
16.32"
10 3872 x 2592 12.91" x 8.64" 19.36" x 12.96" 25.81" x
17.28"
12 4290 x 2800 14.30" x 9.34" 21.45" x 14.00" 28.60" x
18.67"
16 4920 x 3264 16.40" x 10.88" 24.60" x 16.32" 32.80"
x 21.76"
35mm film, scanned 5380 x 3620 17.93" x 12.06" 26.90"
x 18.10" 35.87" x 24.13"
*Typical Resolution. Actual pixel dimensions vary from
camera to camera.
**At 150ppi, printed images will have visible pixels
and details will look "fuzzy".
For a chart of megapixels vs. maximum print size at
300ppi,
see our Megapixels Chart.
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