Container and container product

A container, comprising:

• a container body;
• a cap configured to seal the container body;
• an identification code on a top surface of the cap;
• and
• multiple concaves on the container body,
• wherein:
• the multiple concaves on the container body forms a first image having a first area,
• the identification code on the cap forms a second image having a second area smaller than the first area,
• the container body has a first diffuse reflectance difference between the first image and a portion excluding the first image,
• the identification code has a second diffuse reflectance difference between a code portion and a background portion excluding the code portion in the second image, the second diffuse reflectance difference larger than the first diffuse reflectance difference,
• wherein:
• a visibility value of the first image of the container body containing a content given by an expression [1] below is 14 or less, and
• a symbol contrast of the identification code on the cap given by an expression [2] below is 30% or more,
• visibility value=b0·L*0·(1−exp(b1·ΔL*)), [1]
• where L*0 is a lightness value of the first image,
• ΔL* is a difference between the lightness value of the first image and a lightness value of a portion of the container body excluding the first image,
• b0 is a positive real number, and
• b1 is a negative real number, and
• symbol contrast=|(diffuse reflectance of the background portion)−(diffuse reflectance of the code portion)|. [2]