A few scanning tips


Compute Maximum Image Dimensions
from Megapixels and Aspect Ratio

What are the maximum image dimensions that can fit in X megapixels?

(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, at the bottom. Aspect ratio can be entered in format like 5:4 or 3:2 or 16:9, or it can be the corresponding number like 0.8 or 1.5 or 1.77778 (to 1).

Maximum Pixels from Megapixels

Megapixels   Aspect Ratio
Limit absolute megapixel value (round pixels down)

Limit pixel dimensions to even values

The image at right shows the aspect concept, including the 16:9 format in a 4:3 or 3:2 sensor. That width cannot be wider than the sensor. 16:9 movies will be resampled to 1920x1080 or 1280x720 anyway.

Note that adding just one pixel on the width can add a few thousand pixels on the rows down the height, Coarse steps are involved, so precise final values necessarily can vary slightly.

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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