{"id":1162,"date":"2012-09-03T09:51:34","date_gmt":"2012-09-03T17:51:34","guid":{"rendered":"http:\/\/coldstreams.com\/video\/?p=1162"},"modified":"2012-09-03T09:51:34","modified_gmt":"2012-09-03T17:51:34","slug":"when-megapixels-does-not-mean-what-you-might-think-it-means","status":"publish","type":"post","link":"https:\/\/coldstreams.com\/3d\/2012\/09\/03\/when-megapixels-does-not-mean-what-you-might-think-it-means\/","title":{"rendered":"When “megapixels” does not mean what you might think it means"},"content":{"rendered":"

If your camera has 48 megapixels, how many picture elements do you think your highest resolution photo has?<\/p>\n

This specification table for a Sigma camera<\/a> helps to understand a bit about how “megapixels” may or may not mean what you think it means.<\/p>\n

From the table, this is a 48 megapixel camera (which is an amazing camera).<\/p>\n

But down below, you can see that the highest resolution images are 4704 x 3136 picture elements wide x tall. Multiply those together and you get 14.76 megapixels, not 48 megapixels. Why?<\/p>\n

Because megapixels is counting the sensors of which there are 3 at each pixel. Multiply 14.76 x 3 and you’ll come up with 44.2 million image sensor locations (which is close enough since the entire sensor surface is not used in most cameras). The Foveon sensor<\/a> uniquely has all 3 sensor sites, per pixel stacked on top of one another.<\/p>\n

There’s nothing wrong with these numbers – only a potential misunderstanding of what the term “megapixels” actually means.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
\n
SIGMA DP2 Merrill : Major Specifications<\/strong><\/div>\n<\/td>\n<\/tr>\n
\n
Image Sensor<\/div>\n<\/td>\n
\n
Foveon X3\u00ae direct image sensor (CMOS)<\/div>\n<\/td>\n<\/tr>\n
\n
Image Size<\/div>\n<\/td>\n
\n
23.5\u00d715.7mm<\/div>\n<\/td>\n<\/tr>\n
\n
Number of Pixels<\/div>\n<\/td>\n
\n
Total Pixels:\u00a048MP<\/strong><\/div>\n<\/td>\n<\/tr>\n
\n
Effective Pixels: 46MP(4,800\u00d73,200\u00d73)<\/strong><\/div>\n<\/td>\n<\/tr>\n
\n
Aspect Ratio<\/div>\n<\/td>\n
\n
3:2<\/div>\n<\/td>\n<\/tr>\n
\n
Focal Length<\/div>\n<\/td>\n
\n
30mm<\/div>\n<\/td>\n<\/tr>\n
\n
35mm Equivalent Focal Format<\/div>\n<\/td>\n
\n
Approx. 45mm<\/div>\n<\/td>\n<\/tr>\n
\n
Maximum Aperture<\/div>\n<\/td>\n
\n
F2.8<\/div>\n<\/td>\n<\/tr>\n
\n
Number of Diaphragm Blades 9<\/div>\n<\/td>\n
\n
9 Blades<\/div>\n<\/td>\n<\/tr>\n
\n
Lens Construction<\/div>\n<\/td>\n
\n
8 Elements in 6 Groups<\/div>\n<\/td>\n<\/tr>\n
\n
Minimum Focusing Distance<\/div>\n<\/td>\n
\n
28cm<\/div>\n<\/td>\n<\/tr>\n
\n
Maximum Magnification Shooting<\/div>\n<\/td>\n
\n
1:7.6<\/div>\n<\/td>\n<\/tr>\n
\n
Storage Media<\/div>\n<\/td>\n
\n
SD Card \/ Compatible with SDHC, Multi Media Card<\/div>\n<\/td>\n<\/tr>\n
\n
Recording Mode<\/div>\n<\/td>\n
\n
Lossless compression RAW data (12-bit, High, Medium, Low), JPEG (High, Medium, Low), RAW+JPEG, Movie (motion jpeg), Voice memo to still images (10sec.)<\/div>\n<\/td>\n<\/tr>\n
<\/td>\n<\/td>\n<\/tr>\n
\n
File Size \/ Still<\/div>\n<\/td>\n
\n
<\/div>\n
RAW<\/div>\n<\/td>\n
\n
High<\/strong><\/div>\n<\/td>\n
\n
4,704\u00d73,136\u00d73 (Approx. 45MB)<\/strong><\/div>\n<\/td>\n<\/tr>\n
\n
Medium<\/div>\n<\/td>\n
\n
3,264\u00d72,176\u00d73 (Approx. 24MB)<\/div>\n<\/td>\n<\/tr>\n
\n
Low<\/div>\n<\/td>\n
\n
2,336\u00d71,568\u00d73 (Approx. 12MB<\/div>\n<\/td>\n<\/tr>\n
<\/td>\n<\/td>\n<\/td>\n<\/tr>\n
\n
JPEG<\/div>\n
<\/div>\n<\/td>\n
\n
High<\/div>\n<\/td>\n
\n
Fine 4,704\u00d73,136 (Approx. 10MB)<\/strong><\/div>\n<\/td>\n<\/tr>\n
\n
High Normal 4,704\u00d73,136 (Approx. 5.6MB)<\/div>\n<\/td>\n<\/tr>\n
\n
Basic 4,704\u00d73,136 (Approx. 4.2MB)<\/div>\n<\/td>\n<\/tr>\n
\n
Medium<\/div>\n<\/td>\n
\n
Fine 3,264\u00d72,176 (Approx. 5MB)<\/div>\n<\/td>\n<\/tr>\n
\n
Medium Normal 3,264\u00d72,176 (Approx. 2.7MB)<\/div>\n<\/td>\n<\/tr>\n
\n
Basic 3,264\u00d72,176 (Approx. 2MB)<\/div>\n<\/td>\n<\/tr>\n
\n
Low<\/div>\n<\/td>\n
\n
Fine 2,336\u00d71,568 (Approx. 2.5MB)<\/div>\n<\/td>\n<\/tr>\n
\n
Normal 2,336\u00d71,568 (Approx. 1.4MB)<\/div>\n<\/td>\n<\/tr>\n
\n
Basic 2,336\u00d71,568 (Approx. 1MB)<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Let’s take a look at another camera, the Canon 5D Mark II<\/a>.<\/p>\n

Type
\nHigh-sensitivity, high-resolution, large single-plate CMOS sensor<\/p>\n

Pixels
\nEffective pixels: Approx. 21.1 megapixels<\/p>\n

Total Pixels
\nTotal pixels: Approx. 22.0 megapixels<\/p><\/blockquote>\n

And then look at the image sizes<\/p>\n

File Size
\n(1) Large\/Fine: Approx. 6.1MB (5616 x 3744 pixels)<\/p>\n

(2) Large\/Nomal: Approx. 3.0MB (5616 x 3744 pixels)<\/p>\n

(3) Medium\/Fine: Approx. 3.6MB (4080 x 2720 pixels)<\/p>\n

(4) Medium\/Normal: Approx. 1.9MB (4080 x 2720 pixels)<\/p>\n

(5) Small\/Fine: Approx. 2.1MB (2784 x 1856 pixels)<\/p>\n

(6) Small\/Normal: Approx. 1.0MB (2784 x 1856 pixels)<\/p>\n

(7) RAW: Approx. 25.8MB (5616 x 3744 pixels)<\/p>\n

(8) sRAW 1: Approx. 14.8MB (3861 x 2574 pixels)<\/p>\n

(9) sRAW 2: Approx. 10.8MB (2784 x 1856 pixels)<\/p><\/blockquote>\n

With the Canon 5D Mark II, the image resolution of 5616 x 3744 is 21 megapixels, yet the camera likely has more “photosites” within the imager.<\/p>\n

This leads to the conclusion that megapixel camera ratings do not necessarily \u00a0mean what you think they mean. And that the megapixel count may not be nearly as important as some think it is. Ultimately, lens quality, use of a tripod, sensor noise characteristics and noise removal algorithms, sharpening algorithms and general photographic skill may \u00a0be much more important in image resolution than the megapixel count – however it may be defined.<\/p>\n

 <\/p>\n

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