diff --git a/circuit/grayscale_step.circom b/circuit/grayscale_step.circom
new file mode 100644
index 0000000..fc3bff6
--- /dev/null
+++ b/circuit/grayscale_step.circom
@@ -0,0 +1,97 @@
+pragma circom 2.0.0;
+
+include "utils/row_hasher.circom";
+include "utils/pixels.circom";
+include "node_modules/circomlib/circuits/bitify.circom";
+
+
+template GrayscaleChecker(n) {
+    signal input orig[n][3];
+    signal input gray[n];
+
+    signal output n_check;
+ 
+    component lt[n][2];
+
+    for (var i = 0; i < n; i++) {      
+        var inter = 299 * orig[i][0] + 587 * orig[i][1] + 114 * orig[i][2];
+
+        lt[i][0] = LessEqThan(18);
+        lt[i][1] = LessEqThan(18);
+
+        lt[i][0].in[1] <== 1000;
+        lt[i][0].in[0] <== inter - 1000 * gray[i];
+        lt[i][0].out === 1;
+
+        lt[i][1].in[1] <== 1000;
+        lt[i][1].in[0] <== 1000 * gray[i] - inter;
+        lt[i][1].out === 1; 
+    }
+    n_check <== n;
+}
+
+template GrayScale(width){
+    
+    signal input original[width];
+    signal input transformed[width];
+    
+    component decompressor[width];
+    component decompressor_grey[width];
+    component greychecker[width];
+
+    for (var j=0; j<width; j++) {
+        decompressor[j] = Decompressor();
+        decompressor[j].in <== original[j];
+
+        decompressor_grey[j] = DecompressorGrey();
+        decompressor_grey[j].in <== transformed[j];
+        
+        greychecker[j] = GrayscaleChecker(10);
+        greychecker[j].orig <== decompressor[j].out;
+        greychecker[j].gray <== decompressor_grey[j].out;
+    }
+
+}
+
+template GrayScaleHash(width){
+    signal input ivc_input[2];
+    // signal input prev_orig_hash;
+    // signal input prev_gray_hash;
+    signal output ivc_output[2];
+    // signal output next_orig_hash;
+    // signal output next_gray_hash;
+    
+    // Private inputs
+    signal input external_inputs [2 * width];
+
+    signal row_orig [width];
+    signal row_tran [width];
+
+    for (var i = 0; i < width; i++) {
+        row_orig[i] <== external_inputs[i];
+        row_tran[i] <== external_inputs[i + width];
+    }
+
+    component orig_row_hasher = RowHasher(width);
+    component gray_row_hasher = RowHasher(width);
+    component orig_hasher = Hasher(2);
+    component gray_hasher = Hasher(2);
+
+    orig_row_hasher.img <== row_orig;
+    orig_hasher.values[0] <== ivc_input[0]; // prev_orig_hash
+    orig_hasher.values[1] <== orig_row_hasher.hash;
+    ivc_output[0] <== orig_hasher.hash; // next_orig_hash
+
+    gray_row_hasher.img <== row_tran;
+    gray_hasher.values[0] <== ivc_input[1]; // prev_gray_hash
+    gray_hasher.values[1] <== gray_row_hasher.hash;
+    ivc_output[1] <== gray_hasher.hash; // next_grey_hash
+
+    // grayscale code here ...
+    component checker = GrayScale(width);
+    checker.original <== row_orig;
+    checker.transformed <== row_tran;
+
+}
+
+component main { public [ivc_input] } = GrayScaleHash(128);
diff --git a/circuit/package.json b/circuit/package.json
new file mode 100644
index 0000000..7117d38
--- /dev/null
+++ b/circuit/package.json
@@ -0,0 +1,9 @@
+{
+  "name": "circom",
+  "version": "1.0.0",
+  "main": "index.js",
+  "license": "MIT",
+  "dependencies": {
+    "circomlib": "^2.0.5"
+  }
+}
diff --git a/circuit/utils/pixels.circom b/circuit/utils/pixels.circom
new file mode 100644
index 0000000..b99a828
--- /dev/null
+++ b/circuit/utils/pixels.circom
@@ -0,0 +1,153 @@
+pragma circom 2.0.0;
+include "../node_modules/circomlib/circuits/bitify.circom";
+include "../node_modules/circomlib/circuits/mux1.circom";
+include "../node_modules/circomlib/circuits/comparators.circom";
+
+template Decompressor(){
+    signal input in;
+	signal output out[10][3];
+
+	component toBits = Num2Bits(240);
+	component toNum[10][3];
+
+	toBits.in <== in;
+
+	for (var i=0; i<10; i++) {
+		for (var j=0; j<3; j++) {
+			toNum[i][j] = Bits2Num(8);
+			toNum[i][j].in[0] <== toBits.out[i*24+j*8];
+			toNum[i][j].in[1] <== toBits.out[i*24+j*8+1];
+			toNum[i][j].in[2] <== toBits.out[i*24+j*8+2];
+			toNum[i][j].in[3] <== toBits.out[i*24+j*8+3];
+			toNum[i][j].in[4] <== toBits.out[i*24+j*8+4];
+			toNum[i][j].in[5] <== toBits.out[i*24+j*8+5];
+			toNum[i][j].in[6] <== toBits.out[i*24+j*8+6];
+			toNum[i][j].in[7] <== toBits.out[i*24+j*8+7];
+			out[i][j] <== toNum[i][j].out;
+		}
+	}
+}
+
+template DecompressorKernel(kernel_size){
+    signal input in;
+	signal output out[kernel_size][kernel_size];
+
+	component toBits = Num2Bits(kernel_size*kernel_size*9); // 8-bit value, 1-bit sign
+	component toNum[kernel_size][kernel_size];
+	component selector[kernel_size][kernel_size];
+
+	toBits.in <== in;
+
+	for (var i=0; i<kernel_size; i++) {
+		for (var j=0; j<kernel_size; j++) {
+			toNum[i][j] = Bits2Num(8);
+			toNum[i][j].in[0] <== toBits.out[i*kernel_size*9+j*9];
+			toNum[i][j].in[1] <== toBits.out[i*kernel_size*9+j*9+1];
+			toNum[i][j].in[2] <== toBits.out[i*kernel_size*9+j*9+2];
+			toNum[i][j].in[3] <== toBits.out[i*kernel_size*9+j*9+3];
+			toNum[i][j].in[4] <== toBits.out[i*kernel_size*9+j*9+4];
+			toNum[i][j].in[5] <== toBits.out[i*kernel_size*9+j*9+5];
+			toNum[i][j].in[6] <== toBits.out[i*kernel_size*9+j*9+6];
+			toNum[i][j].in[7] <== toBits.out[i*kernel_size*9+j*9+7];
+			
+			var value = toNum[i][j].out;  // value
+			var sign = toBits.out[i*kernel_size*9+j*9+8];  // sign
+
+			selector[i][j] = Mux1();
+            selector[i][j].c[0] <== value;
+            selector[i][j].c[1] <== 0 - value;
+            selector[i][j].s <== sign;
+
+			out[i][j] <== selector[i][j].out;
+		}
+	}
+}
+
+
+template DecompressorGrey(){
+    signal input in;
+	signal output out[10];
+
+	component toBits = Num2Bits(240);
+	component toNum[10];
+
+	toBits.in <== in;
+
+	for (var i=0; i<10; i++) {
+		var j=0;
+		toNum[i] = Bits2Num(8);
+		toNum[i].in[0] <== toBits.out[i*24];
+		toNum[i].in[1] <== toBits.out[i*24+1];
+		toNum[i].in[2] <== toBits.out[i*24+2];
+		toNum[i].in[3] <== toBits.out[i*24+3];
+		toNum[i].in[4] <== toBits.out[i*24+4];
+		toNum[i].in[5] <== toBits.out[i*24+5];
+		toNum[i].in[6] <== toBits.out[i*24+6];
+		toNum[i].in[7] <== toBits.out[i*24+7];
+		out[i] <== toNum[i].out;
+	}
+}
+
+
+template CompressorCrop(){
+    signal input in[10];
+	signal output out;
+
+	component toNum = Bits2Num(240);
+	component toBits[10];
+
+	for (var i=0; i<10; i++) {
+		toBits[i] = Num2Bits(24);
+		toBits[i].in <== in[i];
+		for (var j=0; j<24; j++) {
+			toNum.in[i*24+j] <== toBits[i].out[j];
+		}
+	}
+	out <== toNum.out;
+}
+
+template DecompressorCrop(){
+    signal input in;
+	signal output out[10];
+
+	component decomp = DecompressorGrey();
+	
+	decomp.in <== in;
+	out <== decomp.out;
+}
+
+template CropInfoDecompressor(){
+	
+	signal input in;
+	signal output row_index;
+	signal output x;
+	signal output y;
+
+	component toBits = Num2Bits(36);
+	component toNumX = Bits2Num(12);
+	component toNumY = Bits2Num(12);
+	component toNumIndex = Bits2Num(12);
+
+	toBits.in <== in;
+	for (var i=0; i<12; i++) {
+		toNumX.in[i] <== toBits.out[i];
+		toNumY.in[i] <== toBits.out[i+12];
+		toNumIndex.in[i] <== toBits.out[i+24];
+	}
+
+	x <== toNumX.out;
+	y <== toNumY.out;
+	row_index <== toNumIndex.out;
+}
+
+
+template Test () {
+	signal input sig1;
+	signal input sig2;
+
+	component decom = Decompressor();
+	decom.in <== sig1;
+	sig2 === decom.out[2][2];
+}
+
+// component main = Test();
diff --git a/circuit/utils/row_hasher.circom b/circuit/utils/row_hasher.circom
new file mode 100644
index 0000000..aa5540e
--- /dev/null
+++ b/circuit/utils/row_hasher.circom
@@ -0,0 +1,30 @@
+pragma circom 2.0.0;
+include "../node_modules/circomlib/circuits/poseidon.circom";
+
+template Hasher(inputSize) {
+    signal input values[inputSize];
+    signal output hash;
+
+    component hasher = Poseidon(inputSize);
+    for (var i = 0; i < inputSize; i++) {
+        hasher.inputs[i] <== values[i];
+    }
+    hash <== hasher.out;
+}
+
+
+template RowHasher (width) {
+    signal input img[width];
+    signal output hash;
+
+    component hasher[width-1];
+
+    for(var i=0; i < width-1; i++) {
+        hasher[i] = Hasher(2);
+        hasher[i].values[0] <== i == 0 ? img[0] : hasher[i-1].hash;
+        hasher[i].values[1] <== img[i+1];
+    }
+
+    hash <== hasher[width-2].hash;
+
+}
\ No newline at end of file