NaturPanorama.ch - Pixel, resolution and quality
Pixel
Each digital (panorama) photo consists of a certain number of pixels.
Example: length x width = 6048 x 4032 pixel.
Pixel size
When a digital photo is printed, the pixels are printed in a different size depending on the length and height of the print in cm.
Example 1: If the 6048 pixels are used for a 1m printout, the size of a printed pixel is 0.16x0.16mm. (= 1000mm / 6048 pixel).
Example 2: If the 6048 pixels are used to print 0.5m length, the size of a printed pixel is 0.08 x0.08mm. (= 500mm / 6048 pixel).
Since the individual pixels are smaller, the printed image from example 2 appears sharper than that from example 1. In practice, we are not talking about the size of the printed pixels, but about the resolution.
Resolution
The resolution in dpi (dot per inch) indicates how many pixels are available over the length of an inch (inch = 25.4mm) for a printout.
Example: 300dpi means that 300 pixels are available for a length of 25.4mm.
The resolution is calculated as follows: Resolution = length in pixels / length in mm * 25.4mm.
For example 1 from chapter Pixel size: 6048pixel / 1000mm * 25.4mm = 153.6 dpi
For example 2 from chapter Pixel size: 6048pixel / 500mm * 25.4mm = 307.2 dpi
The resulting resolution of example 2 is higher than that of example 1.
In most cases, a higher resolution is more desirable than a lower resolution.
Resolution and Quality
Often resolution is equated with technical quality. However, resolution is only one of several criteria which in their sum result in quality. The following criteria are equally important:
- Camera/image sensor used
The camera used is decisive for the quality of a photo. For example, professional cameras produce much better quality than smartphones.
- Lens used
With a high quality lens you get much better technical quality results than with a bad lens.
- Focus on shot
A high resolution is not worth much if the shot is blurred (e.g. focus incorrectly set) or shaky.
- Exposure time for shooting
Too long exposure time leads to overexposure, which in the worst case cannot be corrected. The same applies to too short exposure times.
- Sensitivity (ISO)
If a shot is taken with a too high sensitivity (ISO) (e.g. an evening or morning), image noise results which has a negative effect on the technical quality of an image.
Extrapolating digital photos
If digital images are extrapolated with special software, a small gain in quality can result. This is because, for example, edges are weighted differently than when the digital data is extrapolated 1:1.
But: By extrapolating a digital photo, the result is never more detailed than the original. If, for example, a tree in the original photo is visible as a green area without leaves, the tree will also be visible as a green area in the extrapolated version. The extrapolation does not convert the green area into leaves.
Conclusion
A digital photo taken with a very good equipment (camera and lens) with the optimal settings and a resolution of 200dpi printed out gives better results than a photo taken with a worse camera and/or not optimal settings and 300dpi.