Is megapixels the same thing as resolution, and how should it be described?
Asked 6/27/2017
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What is the correct way to describe an image or camera sensor: “this image is 15 megapixels” or “this image has a resolution of 15 megapixels”? Also, if two images are 5000×4000 and 10000×2000, are those the same resolution because they both total 20 million pixels, or are they different resolutions with the same pixel count?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
9y ago
2 Answers
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Linguistically, "megapixels" is a property of a device or a recording from a device. Properties follow a "has a" relationship, or could be said that "the property ... of ... is ...". Thus, in your situation, it could be equally said,
- The resolution of this image is 15 megapixels; or
- This image has a resolution of 15 megapixels
What it comes down to is our difference in definition of resolution. 5000x4000 and 10000x2000 both come out to 20,000,000. One of us says that these are different resolutions with the same pixel count, and the other says that they are two different resolutions with the same pixel count. What is correct?
Both resolutions are 20 megapixels. They differ in their aspect ratio property, or the ratio of (usually) long dimension to short dimension. Aspect ratio is independent of orientation. Whether your hypothetical images are oriented vertically (portrait) or horizontally (landscape), they have 5:4 and 5:2 aspect ratios, respectively.
Originally by user11924. Source · Licensed CC BY-SA 4.0
user11924
9y ago
0
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Megapixels and resolution are related, but they are not exactly the same thing.
A clear way to say it is:
- “This image has a resolution of 5000×4000 pixels.”
- “This image is 20 megapixels,” or “has a pixel count of 20 megapixels.”
The phrase “resolution of 15 megapixels” is commonly understood, but more precise wording is to use megapixels for total pixel count and use pixel dimensions or ppi/dpi for resolution.
For your example, 5000×4000 and 10000×2000 have the same total pixel count: 20 megapixels. But they are not the same in shape, because they have different aspect ratios. So they are different image dimensions with the same pixel count.
In printing and display contexts, resolution often means pixels per inch (ppi) or dots per inch (dpi), not total megapixels. More generally, optical resolution is about how much detail a system can reproduce, and pixel count is only one factor.
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