Latent Images on Sri Lanka BankNotes

A Latent image is engraved into an intaglio plate and hidden from casual view. They are seen under 10-14X magnification and on 1200 dpi scans shown below. It maybe visible only when the note is held at an particular angle to a light source. Latent images appear to have been first introduced in Sri Lanka with the Rs10 and higher denominations of the 1979 Flora and Fauna series. It is located on all issued regular notes since, except the single lower denomination Rs5 note of 1982 and has not been found on any older notes. It is not used in the 1998 and 2009 commemorative Banknotes.

The term Latent Image was used in Photography for the image on exposed Film before it was developed.
The Latent images are a blur and barely visible at 300 dpi and not visible below 150 dpi

I first learnt about these latent images from Laki Senanayake the Artist of the 1979 notes. CBSL first published about latent images in a Sinhala booklet හොර නෝට්ටු හදුනා ගනිමු (Fake Currency Identification) by Yasapala Perera published in 2003 and in English in book The 70 Year Journey of Currency Issue and Managemant by Shellomi H. Gunawardena and W. M. K. Weerakoon published in 2021.

Democratic Socialist Republic of Sri Lanka : Since 1978 February 4

Flora and Fauna Notes Printed by Bradbury Wilkinson 1979 :
The Numeric value written italic with horizontal lines on vertical line background.
Rs 10 note
Rs 20 note
Rs 50 note
Rs 100 note

Central Bank of Ceylon 1981-1985 :
Historical and Archaeological Notes
Printed byBradbury Wilkinson
The Numeric value written with horizontal lines on vertical line background.
Central Bank of Sri Lanka 1987-1990 :
Historical and Development Notes
Printed byBradbury Wilkinson branch of DeLaRue in Sri Lanka.
The Numeric value written with horizontal lines on vertical line background.
Rs 10 notes Rs 10 notes
Rs 20 notes Rs 20 notes
Rs 50 note Rs 50 notes
Rs 100 note Rs 100 notes
Rs 500 notes Rs 500 notes
Rs 1000  note Rs 1000 notes

Central Bank of Sri LankaNotes: since 1986

Sri Lanka Heritage Notes
Printed byThomas De La Rue Company Limited. in Sri Lanka
1991-1994 :
The Numeric value written with diagonal lines tilted left on a background of diagonal lines tilted right.
1995-2006 :
Advanced Latent Image not clearly visible in scan.
Click to see it highlighted by image processing.
Rs 10 notes cbsl/1991lkh/images/200x_lkh_10r_lie.jpg
Rs 20 notes cbsl/1991lkh/images/200x_lkh_20r_lie.jpg
Rs 50 notes cbsl/1991lkh/images/200x_lkh_50r_lie.jpg
Rs 100 notes cbsl/1991lkh/images/200x_lkh_100r_lie.jpg
Rs 500 notes cbsl/1991lkh/images/200x_lkh_500r_lie.jpg
Rs 1000 notes cbsl/1991lkh/images/200x_lkh_1000r_lie.jpg
Rs 2000 notes The Rs 2000 Note issued only in 2005 had Numeric value written with vertical lines on a background of horizontal lines.

Development, Prosperity and Sri Lankan Dancers Notes
Printed byDeLaRue in Sri Lanka 2010-2021 :
The Numeric value written italic with horizontal lines on vertical line background slightly tilted clockwise.
Rs 20 notes
Rs 50 notes
Rs 100 notes
Rs 500 notes
Rs 1000 notes
Rs 5000 notes

Commemorative issues

CBSL Commemorative Notes
1998 Polymer note Printed by Note Printing Australia
Sri Lanka Independence - 50th Anniversary - Rs 200 notes
commemorative/images/1998_ind50_200r_lie.jpg
Click to see it highlighted by image processing.
2009 The Ushering of Peace and Prosperity in Sri Lanka - Rs 1000 note No Latent Image.
2013 Commonwealth Heads of Government Meeting (CHOGM Sri Lanka) - Rs 500 note Same as regular 2010 Rs500 note that was modified
2018 Sri Lanka 70th Independence - Celebrating Diversity, - Rs 1000 note Same as regular 2010 Rs1000 note that was modified

In 2020 February I followed a Seminar on Counterfeit Currency held by the Central Bank at their Center for Banking Studies. They said there were 3 levels of security features. Those given to the Public, those given to Banks and not the Public, and those known only by the Central Bank. At this seminar which was mainly for Bank employees, which they allowed me to attend, they lectured on the security features given only to banks, which were later published in a book by their employers and I felt free to add it to my web-pages.