diff --git a/scripts/img2scad.html b/scripts/img2scad.html
index b6648975..3feeb3c2 100644
--- a/scripts/img2scad.html
+++ b/scripts/img2scad.html
@@ -4,8 +4,9 @@
 <!--
 Standalone web app to convert an image file to an OpenSCAD array, for use with BOSL2 textures.
 Versions 1-5: 22 April 2025 - by Alex Matulich
+Version 6: 23 April 2025 - added cropping UI
 -->
-  <title>Image to OpenSCAD array, v5</title>
+  <title>Image to OpenSCAD array, v6</title>
   <meta charset="UTF-8">
   <style>
     body { font-family: sans-serif; padding-left:1em; padding-right:1em;}
@@ -61,7 +62,7 @@ Versions 1-5: 22 April 2025 - by Alex Matulich
       visibility: visible;
     }
 
-	/* cropping control panel stuff */
+    /* cropping control panel stuff */
 
     .crop-container {
       display: grid;
@@ -76,7 +77,7 @@ Versions 1-5: 22 April 2025 - by Alex Matulich
       box-sizing: border-box;
       width: fit-content;
       height: fit-content;
-	  margin-top: 8px;
+      margin-top: 8px;
     }
     .crop-center {
       grid-area: center;
@@ -86,7 +87,7 @@ Versions 1-5: 22 April 2025 - by Alex Matulich
       width: 60px;
       height: 60px;
       border: 2px dashed #ccc;
-	  background-color: #eee;
+      background-color: #eee;
       font-weight: bold;
       font-size: 1rem;
       box-sizing: border-box;
@@ -120,7 +121,8 @@ Versions 1-5: 22 April 2025 - by Alex Matulich
 </head>
 <body>
 <h1>Convert image to OpenSCAD array</h1>
-<p>This utility accepts any raster image and converts it to grayscale expanded to use the maximum possible luminance range. Alpha channel is ignored. After resizing, rotating, or reflecting the image as desired, you may save it as an OpenSCAD array.</p>
+<p>This utility accepts any image that can be displayed in your browser, and converts it to grayscale expanded to use the maximum
+possible luminance range. Alpha channel is ignored. After processing the image as desired, you may save it as an OpenSCAD array.</p>
 <hr>
 <div id="content">
   <div class="uiContainer" id="inputArea" tabindex="0">
@@ -146,28 +148,27 @@ Versions 1-5: 22 April 2025 - by Alex Matulich
       <button id="flipHorizontal">⇋ Flip horizontal</button>
       <button id="flipVertical">⇵ Flip vertical</button>
 
-	  <div class="crop-container">
-		<div class="crop-control crop-top">
-		  <label for="crop-top">Top</label>
-		  <input type="number" id="cropTop" min="0" max="9999" value="0">
-		</div>
-		<div class="crop-control crop-left">
-		  <label for="crop-left">Left</label>
-		  <input type="number" id="cropLeft" min="0" max="9999" value="0">
-		</div>
-		<div class="crop-center">Crop</div>
-		<div class="crop-control crop-right">
-		  <label for="crop-right">Right</label>
-		  <input type="number" id="cropRight" min="0" max="9999" value="0">
-		</div>
-		<div class="crop-control crop-bottom">
-		  <input type="number" id="cropBottom" min="0" max="9999" value="0">
-		  <label for="crop-bottom">Bottom</label>
-		</div>
-	  </div>
+      <div class="crop-container">
+        <div class="crop-control crop-top">
+          <label for="crop-top">Top</label>
+          <input type="number" id="cropTop" min="0" max="9999" value="0">
+        </div>
+        <div class="crop-control crop-left">
+          <label for="crop-left">Left</label>
+          <input type="number" id="cropLeft" min="0" max="9999" value="0">
+        </div>
+        <div class="crop-center">Crop</div>
+        <div class="crop-control crop-right">
+          <label for="crop-right">Right</label>
+          <input type="number" id="cropRight" min="0" max="9999" value="0">
+        </div>
+        <div class="crop-control crop-bottom">
+          <input type="number" id="cropBottom" min="0" max="9999" value="0">
+          <label for="crop-bottom">Bottom</label>
+        </div>
+      </div>
 
       <h3>Appearance</h3>
-
       <input type="radio" name="grayModel" value="ntsc" checked><label for "grayModel" class="tooltip"> NTSC grayscale formula
       <span class="tooltiptext">0.299R + 0.587G + 0.114B<br>Based on average human perception of color luminance</span></label><br>
       <input type="radio" name="grayModel" value="linear"><label for="grayModel" class="tooltip"> Linear luminance
@@ -202,8 +203,10 @@ Versions 1-5: 22 April 2025 - by Alex Matulich
 
 </div>
 <hr>
- 
+
   <script>
+    // get page element handles
+
     const imageInput = document.getElementById('imageInput');
     const downloadButton = document.getElementById('downloadButton');
     const resizeWidthInput = document.getElementById('resizeWidth');
@@ -215,37 +218,43 @@ Versions 1-5: 22 April 2025 - by Alex Matulich
     const rotateRightBtn = document.getElementById('rotateRight');
     const flipHorizontalBtn = document.getElementById('flipHorizontal');
     const flipVerticalBtn = document.getElementById('flipVertical');
-	const cropTop = document.getElementById('cropTop');
-	const cropLeft = document.getElementById('cropLeft');
-	const cropRight = document.getElementById('cropRight');
-	const cropBottom = document.getElementById('cropBottom');
+    const cropTop = document.getElementById('cropTop');
+    const cropLeft = document.getElementById('cropLeft');
+    const cropRight = document.getElementById('cropRight');
+    const cropBottom = document.getElementById('cropBottom');
     const blurRadiusInput = document.getElementById('blurRadius');
     const arrayName = document.getElementById('arrayName');
     const inputArea = document.getElementById('inputArea');
     const originalCanvas = document.getElementById('originalCanvas');
     const grayscaleCanvas = document.getElementById('grayscaleCanvas');
 
+    // other initializations
+
     const originalCtx = originalCanvas.getContext('2d');
     const grayscaleCtx = grayscaleCanvas.getContext('2d');
 
-	const cropID = [ cropRight, cropTop, cropLeft, cropBottom ];
-	let edgeID = [ 0, 1, 2 ,3 ];
-	const edgeconfig = [
-	//          noFlip      flipH      flipV     flipV+H
-	/*  0*/ [[0,1,2,3], [2,1,0,3], [0,3,2,1], [2,3,0,1]],
-	/* 90*/ [[3,0,1,2], [1,0,3,2], [3,2,1,0], [1,2,3,0]],
-	/*180*/ [[2,3,0,1], [0,3,2,1], [2,1,0,3], [0,1,2,3]],
-	/*270*/ [[1,2,3,0], [3,2,1,0], [1,0,3,2], [3,0,1,2]]
-	];
+    const cropID = [ cropRight, cropTop, cropLeft, cropBottom ]; // counterclockwise from right
+    let edgeID = [ 0, 1, 2 ,3 ]; // counterclockwise from right: right, top, left, bottom
+    const edgeconfig = [
+	// IDs of crop gadgets corresponding to image edges, from right edge counterclockwise,
+	// in all combinations of rotations and flips.
+    //        no flip     flipH      flipV     flipV+H
+    /*  0*/ [[0,1,2,3], [2,1,0,3], [0,3,2,1], [2,3,0,1]],
+    /* 90*/ [[3,0,1,2], [1,0,3,2], [3,2,1,0], [1,2,3,0]],
+    /*180*/ [[2,3,0,1], [0,3,2,1], [2,1,0,3], [0,1,2,3]],
+    /*270*/ [[1,2,3,0], [3,2,1,0], [1,0,3,2], [3,0,1,2]]
+    ];
     let grayscaleMatrix = [];
     let currentImage = new Image();
     let rotation = 0;
     let flipH = false;
     let flipV = false;
     let fileSuffix = "";
-	let origDim = { width:0, height:0 };
-	let uncropDim = { width:0, height:0 };
-	let cropDim = { width:0, height:0 };
+    let origDim = { width:0, height:0 };
+    let uncropDim = { width:0, height:0 };
+    let cropDim = { width:0, height:0 };
+
+    // image processing functions
 
     function getGrayscaleModel() {
       return document.querySelector('input[name="grayModel"]:checked').value;
@@ -320,8 +329,8 @@ Versions 1-5: 22 April 2025 - by Alex Matulich
       originalSizeText.textContent = `Original size: ${origDim.width}×${origDim.height}`;
 
       // get output image dimensions
-	  uncropDim.width = origDim.width;
-	  uncropDim.height = origDim.height;
+      uncropDim.width = origDim.width;
+      uncropDim.height = origDim.height;
       const newWidth = parseInt(resizeWidthInput.value);
       if (!isNaN(newWidth) && newWidth > 0) {
         uncropDim.width = newWidth;
@@ -358,25 +367,25 @@ Versions 1-5: 22 April 2025 - by Alex Matulich
       const blurRadius = parseInt(blurRadiusInput.value) || 0;
       const blurredMatrix = applyGaussianBlur(brightnessMatrix, blurRadius);
 
-	  // crop the blurred matrix, gather min and max values in crop area
-	  const cropMatrix = [];
-	  let cropx1 = parseInt(cropID[edgeID[2]].value) || 0;
-	  let cropx2 = parseInt(cropID[edgeID[0]].value) || 0;
-	  let cropy1 = parseInt(cropID[edgeID[1]].value) || 0;
-	  let cropy2 = parseInt(cropID[edgeID[3]].value) || 0;
+      // crop the blurred matrix, gather min and max values in crop area
+      const cropMatrix = [];
+      let cropx1 = parseInt(cropID[edgeID[2]].value) || 0;
+      let cropx2 = parseInt(cropID[edgeID[0]].value) || 0;
+      let cropy1 = parseInt(cropID[edgeID[1]].value) || 0;
+      let cropy2 = parseInt(cropID[edgeID[3]].value) || 0;
       let min = 255;
       let max = 0;
-	  for (let y=cropy1; y<uncropDim.height-cropy2; y++) {
+      for (let y=cropy1; y<uncropDim.height-cropy2; y++) {
         const row = [];
         for(let x=cropx1; x<uncropDim.width-cropx2; x++) {
           row.push(blurredMatrix[y][x]);
           min = Math.min(min, blurredMatrix[y][x]);
           max = Math.max(max, blurredMatrix[y][x]);
         }
-		cropMatrix.push(row);
+        cropMatrix.push(row);
       }
-	  cropDim.width = uncropDim.width - cropx1 - cropx2;
-	  cropDim.height = uncropDim.height - cropy1 - cropy2;
+      cropDim.width = uncropDim.width - cropx1 - cropx2;
+      cropDim.height = uncropDim.height - cropy1 - cropy2;
 
       // normalize cropped image brightness to 0-255 range, invert brightness if checkbox is selected
       const range = max - min || 1;
@@ -427,20 +436,28 @@ Versions 1-5: 22 April 2025 - by Alex Matulich
       fileSuffix = finalWidth.toString()+"x"+finalHeight.toString();
     }
 
+	// loading an image
+
+    function resetInputs() { // executed after an image loads
+      cropLeft.value="0";
+      cropRight.value="0";
+      cropTop.value="0";
+      cropBottom.value="0";
+      rotation = 0;
+      flipV = flipH = false;
+      resizeWidthInput.value = "100";
+      blurRadiusInput.value = "0";
+	  invertBrightnessCheckbox.checked = false;
+    }
+
+    // user pressed button to load image from disk
     imageInput.addEventListener('change', function () {
       const file = this.files[0];
       if (file && file.type.startsWith('image/')) {
         const reader = new FileReader();
         reader.onload = function (e) {
           currentImage.onload = function () {
-		    cropLeft.value="0";
-			cropRight.value="0";
-			cropTop.value="0";
-			cropBottom.value="0";
-			rotate = 0;
-			flipV = flipH = false;
-			resizeWidthInput.value = "100";
-			blurRadiusInput.value = "0";
+            resetInputs();
             processImage();
           };
           currentImage.src = e.target.result;
@@ -449,6 +466,7 @@ Versions 1-5: 22 April 2025 - by Alex Matulich
       }
     });
 
+    // user pasted an image from the clipboard into the input area
     inputArea.addEventListener('paste', function (event) {
       const items = (event.clipboardData || event.originalEvent.clipboardData).items;
       for (const item of items) {
@@ -457,6 +475,7 @@ Versions 1-5: 22 April 2025 - by Alex Matulich
           const reader = new FileReader();
           reader.onload = function (e) {
             currentImage.onload = function () {
+			  resetInputs();
               processImage();
             };
             currentImage.src = e.target.result;
@@ -466,85 +485,90 @@ Versions 1-5: 22 April 2025 - by Alex Matulich
       }
     });
 
+    // set up events for all the input gadgets
+
     [resizeWidthInput, invertBrightnessCheckbox, normalizeToUnitCheckbox, blurRadiusInput,
-		...document.querySelectorAll('input[name="grayModel"]')].forEach(el => el.addEventListener('input', processImage));
+        ...document.querySelectorAll('input[name="grayModel"]')].forEach(el => el.addEventListener('input', processImage));
 
-	cropLeft.addEventListener('input', () => {
-		if (!currentImage.src) { cropLeft.value="0"; return; }
-		const cl = parseInt(cropLeft.value) || 0;
-		const cr = parseInt(cropRight.value) || 0;
-		if(uncropDim.width - cl - cr < 2) cropLeft.value = (uncropDim.width - cr - 2).toString();
-		processImage();
-	});
-	cropTop.addEventListener('input', () => {
-		if (!currentImage.src) { cropTop.value="0"; return; }
-		const ct = parseInt(cropTop.value) || 0;
-		const cb = parseInt(cropBottom.value) || 0;
-		if(uncropDim.width - ct - cb < 2) cropTop.value = (uncropDim.height - cb - 2).toString();
-		processImage();
-	});
-	cropRight.addEventListener('input', () => {
-		if (!currentImage.src) { cropRight.value="0"; return; }
-		const cl = parseInt(cropLeft.value) || 0;
-		const cr = parseInt(cropRight.value) || 0;
-		if(uncropDim.width - cl - cr < 2) cropRight.value = (uncropDim.width - cl - 2).toString();
-		processImage();
-	});
-	cropBottom.addEventListener('input', () => {
-		if (!currentImage.src) { cropBottom.value="0"; return; }
-		const ct = parseInt(cropTop.value) || 0;
-		const cb = parseInt(cropBottom.value) || 0;
-		if(uncropDim.width - ct - cb < 2) cropBottom.value = (uncropDim.height - ct - 2).toString();
-		processImage();
-	});
+    cropLeft.addEventListener('input', () => {
+        if (!currentImage.src) { cropLeft.value="0"; return; }
+        const cl = parseInt(cropLeft.value) || 0;
+        const cr = parseInt(cropRight.value) || 0;
+        if(uncropDim.width - cl - cr < 2) cropLeft.value = (uncropDim.width - cr - 2).toString();
+        processImage();
+    });
+    cropTop.addEventListener('input', () => {
+        if (!currentImage.src) { cropTop.value="0"; return; }
+        const ct = parseInt(cropTop.value) || 0;
+        const cb = parseInt(cropBottom.value) || 0;
+        if(uncropDim.width - ct - cb < 2) cropTop.value = (uncropDim.height - cb - 2).toString();
+        processImage();
+    });
+    cropRight.addEventListener('input', () => {
+        if (!currentImage.src) { cropRight.value="0"; return; }
+        const cl = parseInt(cropLeft.value) || 0;
+        const cr = parseInt(cropRight.value) || 0;
+        if(uncropDim.width - cl - cr < 2) cropRight.value = (uncropDim.width - cl - 2).toString();
+        processImage();
+    });
+    cropBottom.addEventListener('input', () => {
+        if (!currentImage.src) { cropBottom.value="0"; return; }
+        const ct = parseInt(cropTop.value) || 0;
+        const cb = parseInt(cropBottom.value) || 0;
+        if(uncropDim.width - ct - cb < 2) cropBottom.value = (uncropDim.height - ct - 2).toString();
+        processImage();
+    });
 
-	function updateEdgeID(out="") {
-		const fi = (flipH ? 1 : 0) + (flipV ? 2 : 0);
-		const ri = Math.round(rotation/90);
-		edgeID = edgeconfig[ri][fi];
-		if (out.length>0) console.log(out, rotation, flipH, flipV, edgeID);
-	}
+    function updateEdgeID(out="") {
+        const fi = (flipH ? 1 : 0) + (flipV ? 2 : 0);
+        const ri = Math.round(rotation/90);
+        edgeID = edgeconfig[ri][fi];
+        if (out.length>0) console.log(out, rotation, flipH, flipV, edgeID);
+    }
 
     rotateLeftBtn.addEventListener('click', () => {
-		if (!currentImage.src) return;
-		rotation = (rotation - 90 + 360) % 360;
-		const tmp = cropTop.value;
-		cropTop.value = cropRight.value;
-		cropRight.value = cropBottom.value;
-		cropBottom.value = cropLeft.value;
-		cropLeft.value = tmp;
-		updateEdgeID();
-		processImage();
-	});
+        if (!currentImage.src) return;
+        rotation = (rotation - 90 + 360) % 360;
+        const tmp = cropTop.value;
+        cropTop.value = cropRight.value;
+        cropRight.value = cropBottom.value;
+        cropBottom.value = cropLeft.value;
+        cropLeft.value = tmp;
+        updateEdgeID();
+        processImage();
+    });
     rotateRightBtn.addEventListener('click', () => {
-		if (!currentImage.src) return;
-		rotation = (rotation + 90) % 360;
-		const tmp = cropTop.value;
-		cropTop.value = cropLeft.value;
-		cropLeft.value = cropBottom.value;
-		cropBottom.value = cropRight.value;
-		cropRight.value = tmp;
-		updateEdgeID();
-		processImage();
-	});
+        if (!currentImage.src) return;
+        rotation = (rotation + 90) % 360;
+        const tmp = cropTop.value;
+        cropTop.value = cropLeft.value;
+        cropLeft.value = cropBottom.value;
+        cropBottom.value = cropRight.value;
+        cropRight.value = tmp;
+        updateEdgeID();
+        processImage();
+    });
     flipHorizontalBtn.addEventListener('click', () => {
-		if (!currentImage.src) return;
-		flipH = !flipH;
-		let tmp = cropRight.value;
-		cropRight.value = cropLeft.value;
-		cropLeft.value = tmp;
-		updateEdgeID();
-		processImage();
-	});
+        if (!currentImage.src) return;
+        flipH = !flipH;
+        let tmp = cropRight.value;
+        cropRight.value = cropLeft.value;
+        cropLeft.value = tmp;
+        updateEdgeID();
+        processImage();
+    });
     flipVerticalBtn.addEventListener('click', () => {
-		if (!currentImage.src) return;
-		flipV = !flipV;
-		let tmp = cropTop.value;
-		cropTop.value = cropBottom.value;
-		cropBottom.value = tmp;
-		updateEdgeID();
-		processImage();
-	});
+        if (!currentImage.src) return;
+        flipV = !flipV;
+        let tmp = cropTop.value;
+        cropTop.value = cropBottom.value;
+        cropBottom.value = tmp;
+        updateEdgeID();
+        processImage();
+    });
+
+    // saving the file - try to use "Save As" file picker, 
+	// fall back to saving with a default name to browser's downloads directory.
 
     downloadButton.addEventListener('click', () => {
       if (grayscaleMatrix.length === 0) return alert("No data to save.");
