Werid lines

[Sun Glaze]

After applying the "change to color" effect in After Effects, why are there strange lines appearing? Please specify the issue.

[Rick Gerard]

The original footage and the Composition are probably both set to 8-bit color. Try changing the comp settings to 16-bit. If that does not give AE enough room in the color space, add a little noise or grain before applying Change Color to hide the banding. 

[Sun Glaze]

from where can I add noise and grain?

[Rick Gerard]

Just search the Effects and Presets. 

Maybe you should spend some time with the User Guide.