To adjust the color of an object(regional adjustment), the simplest way is 'Adj pix mat ref pt color', adjust the pixels that match the color of reference point.

1. Tap  'Adj pix mat ref pt color'. 
2. Tap the petal as the reference point
3. Adjust RGB. The color may change, but only a part of the object.
4. Adjust TR, TG, TB. The T stands for Tolerance. After increasing the values, you can see the adjusted region is expanded. Now it's possible to adjust the entire petals of the flower.

Unfortunately, the flowers of the weed(white dots) are also white. The colors are also replaced with orange. Is it possible to limit the effect region?

Delete the reference point, start all over again.

Tap  and select a polygon. A rectangle is ok for most cases. For complex conditions, you may handcraft a polygon.  Now use 'Adj pix mat ref pt color' and repeat the steps above.

 AndCamera Google Play

This method can be used to make the sky bluer.

 AndCamera Google Play