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View Full Version : Megapixels on Comparison Page



mkgago
03-29-2005, 11:34 AM
First, let me say that I *love* this site. It is far and away the best digital camera review site that I have seen. Fantastic job.

I love the comparison page, which lets users see how various cameras stack up. One suggestion: I realize that max resolution is a more accurate way of stating megapixels, but stating megapixels outright seems like a common-sensical thing, especially for newbies. I understand that one difficulty involved in that would be differentiating between the manufacturer's claimed MPs and the actual MPs. But I wonder if you could set up a simple calculation that would multiply the resolution numbers, move the decimal point, and render a MP number, so that, for example, the entry for the Canon PowerShot A95 would look like this:

Max resolution: 2592 x 1944 (~5.0 MP)

Easier said than done, I know...

ktixx
03-29-2005, 08:59 PM
I love the comparison page, which lets users see how various cameras stack up. One suggestion: I realize that max resolution is a more accurate way of stating megapixels, but stating megapixels outright seems like a common-sensical thing, especially for newbies. I understand that one difficulty involved in that would be differentiating between the manufacturer's claimed MPs and the actual MPs. But I wonder if you could set up a simple calculation that would multiply the resolution numbers, move the decimal point, and render a MP number, so that, for example, the entry for the Canon PowerShot A95 would look like this:

Max resolution: 2592 x 1944 (~5.0 MP)

Easier said than done, I know...

No actually it is actually that easy :) , 2592 x 1944 = 5038848 or 5 million 38 thousand 848 pixels. One MP (mega pixel) = one million pixels, therefor a 5MP camera has 5 million pixels. It is just easier to say 5 Mega Pixels than to say the accurate 5.038848 mega pixels.

Ken

mkgago
03-30-2005, 11:29 PM
lol--I meant that the technical aspect of setting up a script (to multiply the numbers and move the decimal point over), rather than doing each one by hand, is easier said than done...

Geoff Chandler
04-24-2005, 07:35 PM
I made myself a dead simple spreadsheet in exell to do all that for me and put in all the common sizes, and then added a space to put querie sizes - only purely out of curiosity/interest - I scan a lot of my old photos and I can quickly see the equivalent MP value of an image - also if I crop something I can quickly see how much I have reduced it to. One last observation - my KM A-200 is 8mp but if you select the 3:2 'Letter box' size format in 8mp it actually works out at 7mp.

gary_hendricks
04-25-2005, 08:43 AM
Wow, Geoff, anyway I can get that spreadsheet from ya? ;)

Geoff Chandler
04-25-2005, 07:18 PM
Working on nights - I'll see if I can dig it out when I am at home...

Rhys
04-25-2005, 08:24 PM
To convert from megapixels to image size do the following:

divide megapixels by aspect, where aspect is 4:3 or 2:3, dependent on the ccd ratio. Most DSLRs will be 2:3 while most all-in-ones will be 4:3. Thus the aspect will be either 12 or 6 dependent upon the format used (4 x 3 or 2 x 3)

Then take a square root of the result and multiply that by each side of the aspect to get the horizontal and vertical pixels.

Example:

Canon S1 IS. 3 megapixels, 4:3 ratio.

3,000,000 divided by (4 times 3) = 3,000,000 / 12 = 250,000

square root of 250,000 = 500

500 x 4 = 2000
500 x 3 = 1500

The S1 IS is actually 3.2 megapixels giving 2048 x 1536 but my example of 3 dead is easier to understand.

Checking back: 2000 x 1500 is 3,000,000 so the answer is verifiable

Now to take it a stage further to print size, select your optimim print dpi (not printer dpi) and divide the two new figures by that dpi to give the correct print size.

worked example: 2000 x 1500 at 150dpi will yield a print of 13.3 inches by 10 inches.