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Digital Camera Info
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Family and friends often ask my advice on digital cameras. Here's some technical info that you may also find
enlightening.
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Historical Note
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I originally wrote this page back in 2003 when high-res digital cameras first became affordable. The information
is now a little dated, as pretty well
ALL digital cameras now have more than enough resolution to produce high quality prints. Nonetheless, the
information on how large a print can be achieved using various image and print resolutions may still be useful.
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For those technically minded, the following table is explained underneath.
MegaPixels vs Printable Size
How large you could expect to print at typical "Detailed" resolutions?
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Camera
MegaPixels |
Image Size
(Pixels) |
Print Size
@ 200ppi |
Print Size
@ 300ppi |
Print Size
@ 400ppi |
| 1.0 |
1155 x 866 |
5.77" x 4.33" |
3.85" x 2.89" |
2.89" x 1.87" |
| 2.0 |
1633 x 1225 |
8.16" x 6.12" |
5.44" x 4.08" |
4.08" x 3.06" |
| 3.0 |
2000 x 1500 |
10.00" x 7.50" |
6.67" x 5.00" |
5.00" x 3.75" |
| 4.0 |
2309 x 1732 |
11.55" x 8.66" |
7.70" x 5.77" |
5.77" x 4.33" |
| 5.0 |
2582 x 1936 |
12.91" x 9.68" |
8.61" x 6.45" |
6.45" x 4.84" |
| 6.0 |
2828 x 2121 |
14.14" x 10.61" |
9.43" x 7.07" |
7.07" x 5.30" |
| 7.0 |
3055 x 2291 |
15.28" x 11.46" |
10.18" x 7.64" |
7.64" x 5.73" |
| 8.0 |
3266 x 2449 |
16.33" x 12.25" |
10.89" x 8.16" |
8.16" x 6.12" |
| 9.0 |
3464 x 2598 |
17.32" x 12.99" |
11.55" x 8.66" |
8.66" x 6.50" |
| 10.0 |
3651 x 2739 |
18.26" x 13.69" |
12.17" x 9.13" |
9.13" x 6.85" |
| 11.0 |
3830 x 2872 |
19.15" x 14.36" |
12.77" x 9.57" |
9.57" x 7.18" |
| 12.0 |
4000 x 3000 |
20.00" x 15.00" |
13.33" x 10.00" |
10.00" x 7.50" |
| 13.0 |
4163 x 3122 |
20.82" x 15.61" |
13.88" x 10.41" |
10.41" x 7.81" |
| 14.0 |
4320 x 3240 |
21.60" x 16.20" |
14.40" x 10.80" |
10.80" x 8.10" |
| 15.0 |
4472 x 3354 |
22.36" x 16.77" |
14.91" x 11.18" |
11.18" x 8.39" |
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Technical Information
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First off, let's explain some basics:
Image Size:
Digital cameras typically state their resolution in "Megapixels". This is the number of millions of individual
dots of color that are captured. Considering that most images are rectangular (4:3 ratio), this translates into a
few thousand pixels both horizontally and vertically (the exact numbers of which can vary from camera to camera).
Print Size:
The printed size depends on the chosen print resolution in pixels per inch (ppi). Fewer pixels will produce less
detailed printouts, while more pixels (up to a certain point) will produce sharper printouts. The table shows
achievable print sizes based on printing at low resolution (200ppi), medium resolution (300ppi) and high resolution
(400ppi).
Which Resolution?
Many glossy magazines, jewellery catalogues and other materials that we would consider "sharp" are produced with
the images printed at 300ppi. Images can be printed at a lower resolution if they will be viewed from a distance
(eg. when hung on a wall) or at a higher resolution if finer detail is needed. For example:
- 100ppi = Billboards on city streets
- 200ppi = Posters, draft prints
- 300ppi = Glossy magazines, general personal prints
- 400ppi = Fine art books, high detailed prints
- 500ppi = Finest detail (beyond many people's eyesight)
Printer Resolution:
Don't confuse the above image printing resolutions in
ppi (pixels per inch) with print resolutions in
dpi (dots per inch). Most printers need several dots of print resolution to reproduce a single dot of image
resolution. This is because printers typically use only four colors: cyan, magenta, yellow and black. These colors
are "mixed" on the page to simulate the whole spectrum of colors required for reproducing photographic images.
For example, take a typical four-color laser printer. To print a single "tan" pixel from a digital photo of
someone's face may require one dot of cyan ink, two dots of magenta ink, three dots of yellow ink and one dot of
black ink.
A tried-and-tested rule-of-thumb for sharp printouts is to print images at around 1/4 the resolution of the printer.
Thus a typical four-color laser printer, which may have a print resolution of 1200dpi, can produce sharp printouts
from images printed at 300ppi. Printing at any higher density (eg. 400ppi) would simply lose those extra pixels in
the "gaps".
See my
Scanning Graphics page for more information about image and print resolution.
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Other Considerations
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According to the above table, a camera of five megapixels is about the minimum needed to produce sharp prints and
decent enlargements. Why would anyone need more megapixels?
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Moiré:
This is the weird "checkerboard" patterning effect that appears when looking through two mesh screens (such as
flyscreens) in front of each other. Without getting too technical, it's because the holes in the front mesh will
never line up exactly with those in the back mesh due to perspective. One hole may line up with the hole behind
and appear "light", while a hole further across may line up with the mesh behind and appear "dark".
The same effect can happen when taking a digital photo of someone wearing a houndstooth patterned suit, or any fine
checked pattern, or even a coarse weave. This is due to the camera's pixels lining up with either dark or light
parts of the pattern in the cloth.
Having a higher resolution digital camera will reduce the chances of moiré patterns.
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Zooming and Cropping:
Sometimes it is necessary or desirable to zoom in on a portion of an image or to crop something unwanted from an
image. For example:
- Printing one or two faces out of a group shot;
- Zooming in on the detail of a tiny insect;
- Adjusting a sunset scene so that the sun is centered.
All of these examples are effectively discarding a portion of the image. Having plenty of megapixels to start with
means that there will still be sufficent pixels to get a sharp print of the remainder.
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This page last updated: 28-Aug-2010. Copyright © 2003-2010 by
Ian W. Fieggen. All rights reserved.
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