What are the maximum image dimensions that can fit in X megapixels?
What do I get if I buy a 50 megapixel camera?
(It depends on the aspect ratio)
A few standard aspect ratios (1:1, 4:3, 3:2, 16:9) are automatically shown below.
If you enter the other aspect field, it will be shown too, first. Aspect ratio can be entered in format like 5:4 or 3:2 or 11:14, or it can be the corresponding number like 0.8 or 1.414 or 1.77778 (to 1).
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We don't need to know actual pixel size, because all computed Units are "pixels", units of one pixel. The calculator computes maximum WxH image dimensions of various aspect ratios that fit in the same megapixels that you specify.
Image dimensions are necessarily integers of pixels. To add one pixel to width or height can add thousands of pixels to the other. That affects megapixels, which is not allowed here. This goal is to compute maximum dimensions of a specific aspect ratio that fits in specified megapixels. Megapixels is Sensor Area (in pixel units), and since each pixel is the same finite constant size here, therefore all aspect frame sizes of same megapixels are necessarily equal area. All Units are pixels, which DO NOT change size. The math can change the frame diagonal slightly, but in the same megapixel sensor, 3:2 and 4:3 diagonals vary by 2%, and 16:9 and 4:3 vary by 6%.
The blue image here shows the aspect concept visually. The sensor area is WxH, which W and H change with aspect ratio, but their product does not change (megapixels), so their areas do not change (same megapixels, with same pixel size). The plan is, nothing changes but aspect ratio of the sensor.
That of course includes 16:9 video camcorder sensors, but an exception are 16:9 video frames which are contained within existing 4:3 or 3:2 sensors. These of course cannot be the full diagonal (that width cannot be wider than the sensor). And their width could be even smaller (which does reduce field of view), but of course, 16:9 movies will be resampled to 1920x1080 or 1280x720 anyway. The assumption here is that 16:9 in a 4:3 or 3:2 sensor will be as wide as those dimensions allow (which may not be true in all cases).
Rounding pixel dimensions to integers can slightly exceed megapixels (when multiplied by rows), but can be limited to only round down to absolutely limit megapixels to the stated value. Which will be a bit further from the specified megapixel number, but it won't go over.
Pixel dimensions can come out as odd numbers, but can be limited to even numbers. This alone might sometimes be enough to limit megapixels.
Math is precise, but Real World, not so much: If checking the calculator against your camera, realize that cameras round off the specifications. For example, a Microsoft cell phone with 2592 x 1456 pixels specifies 3.77 MP and 16:9 aspect, which computes slightly different dimensions (3 pixels less width). This is because 2592x1456 is actually 3.774 megapixels, and 2592/1456 is actually 1.78 aspect (16:9 is 1.7778). If you enter those actual correct numbers, the calculator shows the exact dimensions (in bold on bottom line).
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