diff --git a/readme.txt b/readme.txt
index a8a4825..ce21890 100644
--- a/readme.txt
+++ b/readme.txt
@@ -9,32 +9,23 @@ i tried to create header with the metadata information of the image
 
 the idea is to simply load image data without worrying about image metadata.
 the metadata contain basic stuff like width, height, format, etc...
-there is also paletteId that tell which palette the image used.
 
-usage: sillyimage <input image> [options]
+color palette are embedded in the file.
+a palette hash is provided. this can be used to comparing
+whether another image uses the same palette
+
+usage: sillyimage -i <input image> -o <output dir> [options]
 
 options:
-  -o, --out
-    output directory
-
-  -f, --format 
-    specify format {rgb256, rgb16, indexed4, indexed16, indexed256, indexed32a3, indexed8a5}
-
-  -c, --compress
-    specify compression {none, lzsswram, lzssvram, gzip}
-
-  -pid, --palette-id
-    specify the palette id
-
-  -n, --num
-    limit num color regardless of the format
-
-  -v, --verbose
-    enable verbose printing
+  -i, --input    input files [required] [may be repeated]
+  -o, --out      output directory [required]
+  -h, --help     shows help message and exits 
+  -v, --version  prints version information and exits 
+  -f, --format   texture format { rgb256, rgb16, indexed4, indexed16, indexed256, indexed32a3, indexed8a5 } [default: "rgb16"]
 
 binary format:
   [string] sillyimg (0x676D69796C6C6973 in hex or 7452728928599042419 in decimal (uint64))
-  [uint8] version (current version is 0)
+  [uint8] version (current version is 13)
   [uint8] format
     0 - RGB256
     1 - RGB16
@@ -44,16 +35,14 @@ binary format:
     5 - INDEXED32A3
     6 - INDEXED8A5
     7 - PALETTE16
-  [uint8] paletteId
   [uint16] width
   [uint16] height
-  [uint8] compression
-    0 - none
-    1 - lzss wram
-    2 - lzss vram
-    3 - gzip
-  [uint32] buffer length
-  [buffer]
+  [uint16] palette count
+  [uint32] palette hash
+  [uint32] compress size
+  [uint32] original size
+  [palette buffer]
+  [image buffer]
 
 TODO:
   [x] bitpacking for indexed format
@@ -61,13 +50,14 @@ TODO:
   [ ] convert image using predefined palette
   [ ] output preview image
   [ ] improve error handling
-  [ ] compression
+  [x] compression
 
-dependecies:
-  argh (https://github.com/adishavit/argh)
-  stb_image, stb_image_writer (https://github.com/nothings/stb)
+dependencies:
+  argparse (https://github.com/p-ranav/argparse)
+  stb_image (https://github.com/nothings/stb)
   libimagequant (https://github.com/ImageOptim/libimagequant)
-  TImer.h from cherno (https://gist.github.com/TheCherno/b2c71c9291a4a1a29c889e76173c8d14)
+  murmurhash.c (https://github.com/jwerle/murmurhash.c)
+  Timer.h from cherno (https://gist.github.com/TheCherno/b2c71c9291a4a1a29c889e76173c8d14)
 
 license:
   GPL v3
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