Pixels, DPI (dots per inch), Resolution and Image Sizes

Dots

dots = pixels on a computer monitor
dots = pixels

Pixels

pixels = dots
pixel = PICture ELement = PICEL = PIXEL

Resolution

resolution = number of pixels horizontally and vertically
resolution example: 
640 x 480 --> 640 pixels horizontal (width) x 480 pixels vertical (height)

Aspect Ratio

aspect ratio = ratio of horizontal to vertical pixel
common aspect ratios:
3:2 = 3 horizontal pixels for each 2 vertical pixels
4:3 = 4 horizontal to 3 vertical (typical for digital cameras & Standard-definition television (SDTV)
16:9 = 16 horizontal to 9 vertical pixels (typical for HDTV)

Frame rate (frame frequency)

frame rate of the device is the speed of production of unique consecutive images (frames).
frame rate units are in frames per second (FPS) and hertz (Hz) for progressive scan monitors.

Common Computer Screen Resolutions (pixel units)
640 x 480
800 x 600
1024 x 768
1280 x 1024
1600 x 1200
1600 x 1280
2048 x 1536
2560 x 2048
3072 x 2304
3200 x 2400
3200 x 2560
3840 x 3072
4096 x 3072
4800 x 3600
4800 x 3840
5120 x 4096
6400 x 4800
6400 x 5120
8000 x 6000
8000 x 6400

Megapixels (MP) pixel count of Digital Cameras

With aspect ratio of 4:3 for most cameras, 4/3 = 1.3333333, four parts for every 3 parts. Example 640/480 = 4/3 = 1.3333333. For computation purposes and derivation, from a 3 MP digital camera, multiply the horizontal pixel by the vertical pixel of the image to determine the total pixel count of the camera. Example,
3 MP: 2048 horizontal x 1536 vertical pixels = 3,145,728 pixels = 3 MP
4 MP: 2272 x 1712 = 3,889,664 = 4 MP
5 MP: 2592 x 1944 = 5,038,848 = 5 MP

Picture Resolution from Kodak Digital Camera:
8.0 MP (4:3): 3264 x 2448 pixels
7.1 MP (3:2): 3264 x 2176 pixels
6.0 MP (16:9): 3264 x 1836 pixels
5.0 MP (4:3): 2592 x 1944 pixels
3.1 MP (4:3): 2048 x 1536 pixels
2.2 MP (3:2): 1800 x 1200 pixels
2.1 MP (16:9): 1920 x 1080 pixels
1.2 MP (4:3): 1280 x 960 pixels

Video Capture Resolution from Kodak Digital Camera:
VGA (640 x 480 @ 30 fps)
QVGA (320 x 240 @ 30 fps)

Digital Television High Definition (HD) Video Formats (16:9 aspect ratio HDTV):
720p --> 1280 x 720 pixels
1080i --> 1920 x 1080 pixels
1080p --> 1920 x 1080 pixels (24, 25, 30, 50, 60 Hz frame rate)

Extra high-definition video
2000p --> 2,048 × 1,536 pixels (24 Hz frame rate)
2160p --> 3,840 × 2,160 pixels (60, 120 Hz frame rate)
2540p --> 4,520 × 2,540 pixels
4000p --> 4,096 × 3,072 pixels
4320p --> 7,680 × 4,320 pixels (60, 120 Hz frame rate)

Samsung digital camera storage image size:
10M: 3648 x 2736 pixels
8M: 3264 x 2448 pixels
7M: 3648 x 2052 pixels
5M: 2592 x 1944 pixels
3M: 2048 x 1536 pixels
2M: 1920 x 1080 pixels
1M: 1024 x 768 pixels

Digital Camera Picture Resolutions:
160 MP --> 21,250 x 7500 pixels [from Seitz (highest megapixel camera)]
120 MP --> 13,280 x 9,184 pixels (from Canon)
100 MP --> 11,547 X 8660 pixels
80 MP --> 10,328 x 7760 pixels
60 MP --> 8984 x 6732 pixels
50 MP --> 8176 x 6132 pixels
40 MP --> 7264 x 5440 pixels
36 MP --> 7360 x 4912 pixels
24 MP --> 6000 x 4000 pixels
20 MP --> 5120 x 3840 pixels
18 MP --> 5184 x 3456 pixels
16 MP --> 4592 x 3448 pixels
14 MP --> 4288 x 3216 pixels
12 MP --> 4000 x 3000 pixels
10 MP --> 3648 x 2736 pixels
8 MP --> 3264 x 2448 pixels
7 MP --> 3648 x 2052 pixels
6 MP --> 3000 x 2000 pixels

Photo Resolution of Smartphones:
8 MP --> 3264 x 2448 pixels
7 MP --> 3648 x 2052 pixels
6 MP --> 3000 x 2000 pixels
5 MP --> 2560 X 1920 pixels
4 MP --> 2560 X 1536 pixels
3 MP --> 2048 X 1536 pixels
2.4 MP --> 2048 X 1232 pixels
2 MP --> 1600 X 1200 pixels
1.5 MP --> 1600 X 960 pixels
0.5 MP --> 800 X 600 pixels
0.4 MP --> 800 X 480 pixels
0.3 MP --> 640 X 480 pixels

Maximum Print Sizes of Photos from Digital Cameras at 300 DPI
2MP: 1600 x 1200 --> 5.3 X 4.0 inches
3MP: 2048 x 1536 --> 6.8 X 5.1 inches
5MP: 2592 x 1944 --> 8.6 X 6.4 inches
7MP: 3072 x 2304 --> 10.2 X 7.6 inches
8MP: 3264 x 2448 --> 10.8 X 8.1 inches <-- 8X10 Wall Pictures at home
10MP: 3648 x 2736 --> 12.1 X 9.1 inches
12MP: 4000 x 3000 --> 13.3 X 10 inches
14MP: 4288 x 3216 --> 14.2 X 10.7 inches


How to convert from pixels to inches:

300 DPI is recommended for most prints by photo professionals. Conversion from pixels to inches depends on the dots per inch (dpi).

At 300 dpi printer output resolution:

4x6 inches (10x15 cm) prints:
4 inch x 300 dots/inch = 1200 dots = 1200 pixels width
6 inch x 300 dots/inch = 1800 dots = 1800 pixels height
therefore:
4x6 inches = 1200 x 1800 pixels

5x7 inches (12.5 x 17.5 cm) prints:
5 x 300 = 1500 pixels width
7 x 300 = 2100 pixels height
therefore:
5x7 inch = 1500 x 2100 pixels

8" x 10" (20x25 cm) prints:
8 x 300 = 2400 pixels width
10 x 300 = 3000 pixels height
therefore:
8x10" = 2400 x 3000 pixels