When an logarithmic transform can be applied to an image

i am using the below statement for logarithmic transform. z(x,y)=c.*log10(1+m);

How to identify the value of C in the above statement.

Under what circumstances logarithmic transform can be applied to an image

Answer 1

[Walter Roberson]

If you do not know the potential range of m then you cannot estimate c.

If you know all of the unique m and z values, then you could

c_estimated = mean( unique_z ./ log10(1+unique_m) );

(However if any z value is negative then c must be negative and you would need to sort z in the opposite direction.)

"Under what circumstances logarithmic transform can be applied to an image"

The image values must be converted to floating point class, either using double() or using im2double().

It might not make much sense to apply a logarithmic transform in very many situations, but that is a different matter than asking when a logarithmic transform can be applied.