Update README.md

@@ -64,16 +64,18 @@ Our Proposed Codec
 
 Performance Test
 -------------
-#### PSNR
+#### PSNR (Peak Signal to Noise Ratio)
 ![ex_screenshot](./PSNR.png)
-#### MS-SSIM
+#### MS-SSIM (multi-scale Structural SIMilarity)
+구조적 유사도 지수
 #### BPP
 (#압축에 사용된 전체 Bit 수) / (#전체 화소수)       
 #### RD-Curve
   MSE Curve  |  MS-SSIM Curve
 :-------------------------:|:-------------------------:
 ![anchor_curve](./RD_curve.PNG)  |  ![ms-ssim_curve](./RD_curve_msssim.PNG)
-#### BD-rate
+#### BD-rate (Bjontegaard-Delta rate)
+
 
 Code explanation
 -------------