How do I know if an image is suitable to converted into Black and White. Its easy! 
First, I look to see if there is a general hue or tone to the image. Does the scene have a blue cast,such as on a cold day. Is there fog present in the image. Are the colors muted or do the colors look washed out? Or are there warm colors(yellows,reds or oranges)? Is everything green? These are all indications that the photograph might work well in black and white.

I also will squint my eyes to decrease the colors reaching my eyes. This will help create a colorless scene.

I will also look to see if the image is very busy. Are there green leaves everywhere? Are there any colors that jump out at me? Is there a lot of contrast in the image?

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