What is the significance of the Signed or Unsigned Char Pixel Type for Raster images?

[Craig_Eissler_Iceman]

Hello,

I've worked with quite a few Raster datasets in the past, but not so much of the Imagery kind.

I see that these Raster Images have Integer numerical values that are either "signed" and can store negative values, or they are "unsigned" and cannot -- meaning they only store positive values. I also see that the range of values depends on the number of Bits.

But "What is the significance of the Signed/Unsigned Char Pixel Type for Raster images?"
In other words, what does it mean? Why should I care? 

Thanks,

[GlenterpriseUK]

@Craig_Eissler_Iceman 

I believe that the difference in Signed/Unsigned pixel type defines the bit depth and value range of each pixel in a raster image.

Unsigned character can be used for things like satellite imagery or aerial photos

Signed character can be used for things like mapping temperature or elevation differences

Bit depth capacity for raster dataset pixels—ArcGIS Pro | Documentation

Why is relevant to ArcGIS Pro is because the pixel type is used to determine how the raster values are stretched and displayed. If for a specific theme you use incorrect pixel type the result can be a poor visualization.

Regards,

Glen

[Craig_Eissler_Iceman]

Ok, thanks.

But why have the differntiation at all? In other words, why not let Values be whatever they are, positive or negative? 

...Or is restricting Imagery (Photos, Infrared, etc.) to positive numbers (Unsigned) just what you have to do for those Pixels to make sense?

...Also, why would Elevation or Temperature pixels need this Type? In other words, why wouldn't Floating Points or Integers be suitable?