picture rejected : help me understand

[vavawelcom]

Hello,
I'm brand new on this web site. I just submitted 3 pictures and two of them were rejected because of "picture grain / noise".
Could you help me understand please ?

[Szalam]

At first I thought maybe all the concrete looked like noise, but when I looked at your image at 100% zoom I could see the digital noise is present throughout. The noise is kind of disguised in the rough areas, but it's quite obvious in the area that's relatively smooth.

[MatHayward]

Is this an image of graffiti art? If so, regardless of noise you would need a property release to sell this photo.

-Mat