to recognise the chip. So dealers with bad eyes also know which denominations they are giving away.
Before the chipping machine was introduced in the casino of Knokke all chips were sorted by hand.
In the summer it happened that a roulette chip from table 2 was between the colored roulette chips of table 1.
So when chipping (putting the chips in stacks of 20) the picture on the chip did not really matter.

JO from Belgium