Add semi-transparent overlay on imageview

Set your imageview like this::

<ImageView
android:id="@+id/imageview"
android:layout_width="wrap_parent"
android:layout_height="wrap_parent"
android:foreground="@drawable/image_overlay"
android:src="@drawable/your_image" />

image_overlay.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <gradient
        android:startColor="#401C87C0"
        android:centerColor="#401C87C0"
        android:endColor="#401C87C0"
        />
</shape>

I use color-code = #1C87C0 and set it to 25% opacity so the final color-code be like #401C87C0. You can change color opacity changing the first 2 characters in the color definition according to your requirement ::

100% — FF
99% — FC
98% — FA
97% — F7
96% — F5
95% — F2
94% — F0
93% — ED
92% — EB
91% — E8

90% — E6
89% — E3
88% — E0
87% — DE
86% — DB
85% — D9
84% — D6
83% — D4
82% — D1
81% — CF

80% — CC
79% — C9
78% — C7
77% — C4
76% — C2
75% — BF
74% — BD
73% — BA
72% — B8
71% — B5

70% — B3
69% — B0
68% — AD
67% — AB
66% — A8
65% — A6
64% — A3
63% — A1
62% — 9E
61% — 9C

60% — 99
59% — 96
58% — 94
57% — 91
56% — 8F
55% — 8C
54% — 8A
53% — 87
52% — 85
51% — 82

50% — 80
49% — 7D
48% — 7A
47% — 78
46% — 75
45% — 73
44% — 70
43% — 6E
42% — 6B
41% — 69

40% — 66
39% — 63
38% — 61
37% — 5E
36% — 5C
35% — 59
34% — 57
33% — 54
32% — 52
31% — 4F

30% — 4D
29% — 4A
28% — 47
27% — 45
26% — 42
25% — 40
24% — 3D
23% — 3B
22% — 38
21% — 36

20% — 33
19% — 30
18% — 2E
17% — 2B
16% — 29
15% — 26
14% — 24
13% — 21
12% — 1F
11% — 1C

10% — 1A
9% — 17
8% — 14
7% — 12
6% — 0F
5% — 0D
4% — 0A
3% — 08
2% — 05
1% — 03
0% — 00 

You can surround your ImageView within a FrameLayout.

    <FrameLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:foreground="@color/semi_transparent_color">

        <ImageView
            android:layout_width="200dp"
            android:layout_height="200dp"
            android:src="@drawable/your_image" />
    </FrameLayout>

You can use a semi-transparent color here, maybe something like #22000000.