diff --git a/Sources/Internal/RCImageDecoder.swift b/Sources/Internal/RCImageDecoder.swift
index 3729c8b..de27fc9 100644
--- a/Sources/Internal/RCImageDecoder.swift
+++ b/Sources/Internal/RCImageDecoder.swift
@@ -25,6 +25,7 @@ import UIKit
 final class RCImageDecoder {
 
   var size = 0
+  lazy var sectionSize = self.size / 5
 
 }
 
@@ -32,7 +33,6 @@ extension RCImageDecoder {
   func process(pointer: UnsafeMutablePointer<UInt8>) throws -> [RCBit] {
     let bufferData = UnsafeMutableBufferPointer<UInt8>(start: pointer, count: size * size)
     let data = RCMatrix<UInt8>(rows: size, items: bufferData)
-    let sectionSize = size / 5
     let sectors = Side.allCases.map { side -> (side: Side, x: Int, y: Int) in
       switch side {
         case .top:
diff --git a/Sources/Public/RCCameraViewController.swift b/Sources/Public/RCCameraViewController.swift
index ea93539..9c3e588 100644
--- a/Sources/Public/RCCameraViewController.swift
+++ b/Sources/Public/RCCameraViewController.swift
@@ -103,6 +103,7 @@ extension RCCameraViewController {
     super.viewDidLayoutSubviews()
     configureMaskLayer()
     videoPreviewLayer?.frame = view.bounds
+    calculateScanArea()
   }
 }
 
@@ -147,6 +148,7 @@ extension RCCameraViewController {
     do {
       captureSession.sessionPreset = .hd1280x720
       coder.set(size: 720)
+      calculateScanArea()
       let input = try AVCaptureDeviceInput(device: captureDevice)
       input.device.activeVideoMaxFrameDuration = CMTimeMake(value: 1, timescale: 30)
       captureSession.addInput(input)
@@ -159,6 +161,14 @@ extension RCCameraViewController {
     }
   }
   
+  private func calculateScanArea() {
+    let actualWidth = view.frame.height / 16 * 9
+    var sideArea: CGFloat = min(view.bounds.width, view.bounds.height) * 0.9 * 0.2
+    sideArea += (actualWidth - min(view.bounds.width, view.bounds.height) * 0.9) / 2
+    let area = sideArea / min(view.bounds.width, view.bounds.height) * 720
+    coder.set(scanArea: Int(area))
+  }
+  
   private func configureVideoPreview(orientation: AVCaptureVideoOrientation = .portrait) {
     videoPreviewLayer?.removeFromSuperlayer()
     videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
diff --git a/Sources/Public/RCCoder.swift b/Sources/Public/RCCoder.swift
index 33c7362..4775f34 100644
--- a/Sources/Public/RCCoder.swift
+++ b/Sources/Public/RCCoder.swift
@@ -64,4 +64,8 @@ extension RCCoder {
   func set(size: Int) {
     imageDecoder.size = size
   }
+  
+  func set(scanArea: Int) {
+    imageDecoder.sectionSize = scanArea
+  }
 }