Soviet Era Photos II

Following up Soviet Era Photos, another eBay seller has offered a number of interesting photos on eBay: Show only: Items from seller glad9.

The description for this photo said, 'USSR Russia Latvia Riga. 25th chess championship of the USSR. Grandmasters Bukhuti Gurgenidze and Semjon Furman. Original vintage photo. Photographers by V. Veders. Approx. size 4,75 x 7,25 inc (12 x 18,5 cm). Very good/fine condition.' For more about the event pictured, see Graeme Cree's 25th USSR Championship and Zonal.

What causes the halo effect around the heads?