Some advice about rejected photos will be aprecciatted.

Hi juanpirulo,

These images are really nice. To inspect for noise, artifacts, sharpness, and etc, you need to zoom your images up between 100 and 200% to find these issues. Grains are identified by multiple of small spots/dots that can be seen in dark or lighted areas. Some noise forms are blotches within black areas. Your colors should be smooth. You may use an editing software to correct noise. This is made easier if your photos are taken in RAW.

Best wishes

JG

Hello,

In these images, look at the sky areas. It shows posterisation - or banding. This is when the tonal graduation between the colours is not gradual. One tone turns into another more abruptly. This happens when working with 8-bit images - typical from a JPEG image. 

You also have signs of noise/JPEG compression throughout the images - a bit hard to tell at these resolutions. Were these photos taken on a smartphone?