Correlation between MUA or LFP signal and basic image properties
MUA
property	mean	s.d.
mean pixel intensity	0.07	0.09
s.d. pixel intensity	0.01	0.02
s.d./mean pixel intensity	0.04	0.05
nr of non-gray pixels	0.01	0.02
number of bright pixels (intensity>128)	0.03	0.05
number of dark pixels (intensity<128)	0.01	0.02
number of very bright pixels (intensity>200)	0.04	0.05
number of very dark pixels (intensity<56)	0.01	0.02
number of non-black pixels	0.04	0.05
mean pixel intensity within the object	0.01	0.02
s.d. pixel intensity within the object	0.03	0.04
minimum pixel intensity within the object	0.01	0.02
maximum pixel intensity within the object	0.03	0.04
pixel intensity range	0.01	0.02
contrast	0.04	0.05
total power	0.01	0.02
LFP
property	mean	s.d.
mean pixel intensity	0.04	0.04
s.d. pixel intensity	0.07	0.02
s.d./mean pixel intensity	0.04	0.05
nr of non-gray pixels	0.01	0.02
number of bright pixels (intensity>128)	0.04	0.05
number of dark pixels (intensity<128)	0.01	0.02
number of very bright pixels (intensity>200)	0.06	0.08
number of very dark pixels (intensity<56)	0.01	0.02
number of non-black pixels	0.02	0.03
mean pixel intensity within the object	0.01	0.02
s.d. pixel intensity within the object	0.02	0.03
minimum pixel intensity within the object	0.01	0.02
maximum pixel intensity within the object	0.02	0.03
pixel intensity range	0.01	0.02
contrast	0.03	0.04
total power	0.01	0.02
mean indicates the percentage of the variance explained by each simple image propery (average across sites)
s.d. indicates the percentage of the variance explained by each simple image property (average across sites)