In the video images and computer graphics

Gamma correction is an important process realizing images vision information of reproduction source objects truly.So

the principle of Gamma correction in OLED/LCD is described.By considering human being's vision non-linear

get the formula of gray and luminance

that is

G

=

K

×(

L

)

(1/2.2)

.At the same time

get the characteristic curve of gray-scale and luminance of CRT relative to OLED and LCD.According to OLED and LCD electro-optical non-linear curves

we adopt normalized method to correction.Besides

in the practical

two conditions are limited.One is the gradient of OLED and LCD electro-optical curves.If their gradient is very steep

the adjacent gray-scale voltage will be very close.Thus

maximum noise voltage is limited in the electrical circuit.Another is the complication of the electrical circuit.If each gray-scale voltage depends on driving circuit directly

it will be very difficult to make the driving circuit to multi-gray scale display.Therefore

usually some regulation voltages of gray-scale are selected.But other gray-scale voltages are selected by row resistors average between adjacent regulation voltages.In fact

the practical gray-scale voltages are an approximation by gamma correction.The more the quantity of regulation voltage is

the better the gamma correction voltages are.Due to the comparability of OLED and LCD correction

here we have an example of correcting TFT LCD of 26.4 cm VGA(line inversion).Source driver IC is μPD16641 of NEC corporation.It has eleven voltages as regulation voltages of Gamma correction.Its driving method is line inversion.We can see its configuration diagram and gamma correction circuit.From the relation diagram of input data

gray-scale and regulation voltages

get external voltage setting values of γ correction in driving circuits were obtained.By comparing the setting and measured values

they are very adjacent in result.