|In this photo the sky is flat and grayish.|
|Your image now looks completely blue with the bull on the |
lower layer obscured by the blue sky.
With "Blend If" set to Gray, slide the black triangle on the left for the "Underlying Layer" to the right until the blue fills only the area of the sky and none, or almost none, of the subject of the image. Above you can see I have moved the left slider over to the right to the point where its value reads 205. Some blue is still showing through on the bull's nose, and a little bit by the ear on the right. We'll take care of that next.
|Touch up your final image by using a layer mask to hide any pieces of blue sky that show through the subject.|
To remove the traces of blue still showing through on the bull, add a layer mask to the blue sky layer and paint with black on the mask to hide any traces of the blue sky that is still showing through. You're done and now you have an image with improved blue sky thanks to Photoshop! Thank you, Photoshop!