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== magnification and resolution == | == magnification and resolution == | ||
To find out how big the surface is we are looking at, we are capturing a piece of a screen/display and count the pixels. We tried an [[wikipedia:iPod|iPod | To find out how big the surface is we are looking at, we are capturing a piece of a screen/display and count the pixels. We tried an [[wikipedia:iPod Touch|iPod Touch]] which has a widescreen with the following specs: | ||
* resolution is 960 x 640 pixels | |||
* resolution 960 x 640 pixels | * physical size is 75 x 50 mm | ||
* | Hence we can calculate the pixel density of the device: | ||
* 0,078125 mm per pixel (or 12,8 pixels per mm) | * 0,078125 mm per pixel (or 12,8 pixels per mm) | ||
[[File:iPod touch screen.png|150px]] | [[File:iPod touch screen.png|150px]] | ||
On our screen capture through the microscope we see approximately 5,8 x 4,2 pixels of the screen (one pixel consists of a triplet of red green and blue). Now we know that we are looking at a surface of ~ 0,45 x 0,33 mm. | On our screen capture through the microscope we see approximately 5,8 x 4,2 pixels of the screen (one pixel consists of a triplet of red, green and blue). Now we know that we are looking at a surface of ~ 0,45 x 0,33 mm. | ||
To calculate the magnification factor the pixel density of the display must be taken into account. | To calculate the magnification factor the pixel density of the display must be taken into account. | ||