Keyword Analysis & Research: why do my png images have a black background

Keyword Analysis

Keyword	CPC	PCC	Volume	Score	Length of keyword
why do my png images have a black background	1.86	0.8	1974	35	44
why	1.15	1	6938	96	3
do	0.86	0.3	2171	57	2
my	1.38	0.1	8290	65	2
png	1.6	0.3	853	80	3
images	0.58	1	5038	96	6
have	0.97	0.5	6629	77	4
a	1.24	0.7	5772	9	1
black	1.75	0.7	2766	46	5
background	0.54	0.9	4656	78	10

Keyword	CPC	PCC	Volume	Score
why do my png images have a black background	0.11	0.4	2553	98