Megapixels Resolution in PPI

Megapixels Resolution in PPI

Now a days IP Camera markets going to use 7MP, 10MP, 16MP resolution for Better background information (photo quality).

The first things to understand is that in digital imaging, the only thing that really counts about a file is how many pixels are in a file. Terms like megapixels, DPI and file sizes in megabytes only confuse the issue. In the end, all digital images are simply X pixels by Y pixels big (by Z bits of colour data but we can ignore that for now)

Pixels Per Inch is the key term. It is a description of the logical number of pixels from your original image (X pixels by Y pixels, remember) that will be used to tell the printer to print one inch on paper. Assuming a sharp original shot with good technique (see resolution discussion below), the higher the PPI, the better the quality print you can achieve - this is testably true even well beyond most claims of 360 PPI being the most you need ... 600 PPI images can easily be seen to be much sharper again if this data is available at good quality from the original file).

Here's why:

1. A megapixel is 1 million pixels. It's an area measurement like square feet.
2. 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.

3.  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
4.  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

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"
36, Nikon D800	7360 x 4912	24.53" x 16.37"	36.80" x 24.56"	49.06" x 32.74"

*Typical Resolution. Actual pixel dimensions vary from camera to camera.
**At 150ppi, printed images will have visible pixels and details will look "fuzzy".

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