diff --git a/src/app.js b/src/app.js
index 8d87ad8..c364e08 100644
--- a/src/app.js
+++ b/src/app.js
@@ -18,10 +18,75 @@ const canvas = make_canvas();
 canvas.classList.add("main-canvas");
 const ctx = canvas.ctx;
 
-const default_palette = [
+// these colors I think I got from a VM screenshot, but maybe the VM shifted the colors with a color filter
+// they're slightly off, and incompatible with mspaint as far as the fill tool goes
+const old_inaccurate_default_palette = [
 	"#000000","#787878","#790300","#757A01","#007902","#007778","#0A0078","#7B0077","#767A38","#003637","#286FFE","#083178","#4C00FE","#783B00",
 	"#FFFFFF","#BBBBBB","#FF0E00","#FAFF08","#00FF0B","#00FEFF","#3400FE","#FF00FE","#FBFF7A","#00FF7B","#76FEFF","#8270FE","#FF0677","#FF7D36",
 ];
+
+const default_palette = [
+	"rgb(0,0,0)", // Black
+	"rgb(128,128,128)", // Dark Gray
+	"rgb(128,0,0)", // Dark Red
+	"rgb(128,128,0)", // Pea Green
+	"rgb(0,128,0)", // Dark Green
+	"rgb(0,128,128)", // Slate
+	"rgb(0,0,128)", // Dark Blue
+	"rgb(128,0,128)", // Lavender
+	"rgb(128,128,64)", //
+	"rgb(0,64,64)", //
+	"rgb(0,128,255)", //
+	"rgb(0,64,128)", //
+	"rgb(64,0,255)", //
+	"rgb(128,64,0)", //
+
+	"rgb(255,255,255)", // White
+	"rgb(192,192,192)", // Light Gray
+	"rgb(255,0,0)", // Bright Red
+	"rgb(255,255,0)", // Yellow
+	"rgb(0,255,0)", // Bright Green
+	"rgb(0,255,255)", // Cyan
+	"rgb(0,0,255)", // Bright Blue
+	"rgb(255,0,255)", // Magenta
+	"rgb(255,255,128)", //
+	"rgb(0,255,128)", //
+	"rgb(128,255,255)", //
+	"rgb(128,128,255)", //
+	"rgb(255,0,128)", //
+	"rgb(255,128,64)", //
+];
+const monochrome_palette_as_colors = [
+	"rgb(0,0,0)",
+	"rgb(9,9,9)",
+	"rgb(18,18,18)",
+	"rgb(27,27,27)",
+	"rgb(37,37,37)",
+	"rgb(46,46,46)",
+	"rgb(55,55,55)",
+	"rgb(63,63,63)",
+	"rgb(73,73,73)",
+	"rgb(82,82,82)",
+	"rgb(92,92,92)",
+	"rgb(101,101,101)",
+	"rgb(110,110,110)",
+	"rgb(119,119,119)",
+
+	"rgb(255,255,255)",
+	"rgb(250,250,250)",
+	"rgb(242,242,242)",
+	"rgb(212,212,212)",
+	"rgb(201,201,201)",
+	"rgb(191,191,191)",
+	"rgb(182,182,182)",
+	"rgb(159,159,159)",
+	"rgb(128,128,128)",
+	"rgb(173,173,173)",
+	"rgb(164,164,164)",
+	"rgb(155,155,155)",
+	"rgb(146,146,146)",
+	"rgb(137,137,137)",
+];
 let palette = default_palette;
 let polychrome_palette = palette;
 let monochrome_palette = make_monochrome_palette();
@@ -50,6 +115,25 @@ let custom_colors = [
 	"#FFFFFF", "#FFFFFF", "#FFFFFF", "#FFFFFF", "#FFFFFF", "#FFFFFF", "#FFFFFF", "#FFFFFF",
 ];
 
+let inaccurate_palette_rgbas = old_inaccurate_default_palette.map(get_rgba_from_color);
+let accurate_palette_rgbas = default_palette.map(get_rgba_from_color);
+const exclude_rgbas = (rgbas, exclude_rgbas)=>
+	rgbas.filter((rgba)=>
+		!exclude_rgbas.find((exclude_rgba)=>
+			rgba.join(",") === exclude_rgba.join(",")
+		)
+	);
+const intersect_rgbas = (rgbas1, rgbas2)=>
+	rgbas1.filter((rgba1)=>
+		rgbas2.find((rgba2)=>
+			rgba1.join(",") === rgba2.join(",")
+		)
+	);
+const neutral_rgbas = intersect_rgbas(accurate_palette_rgbas, inaccurate_palette_rgbas);
+inaccurate_palette_rgbas = exclude_rgbas(inaccurate_palette_rgbas, neutral_rgbas);
+accurate_palette_rgbas = exclude_rgbas(accurate_palette_rgbas, neutral_rgbas);
+// console.log({neutral_rgbas, inaccurate_palette_rgbas, accurate_palette_rgbas});
+
 // declared like this for Cypress tests
 window.default_brush_shape = "circle";
 window.default_brush_size = 4;
diff --git a/src/functions.js b/src/functions.js
index 2b9d8e6..94f1bf5 100644
--- a/src/functions.js
+++ b/src/functions.js
@@ -692,6 +692,11 @@ function open_from_Image(img, callback, canceled){
 		current_history_node.image_data = ctx.getImageData(0, 0, canvas.width, canvas.height);
 		current_history_node.icon = null; // @TODO
 
+		// creates an undoable; must go after manual current_history_node manipulation
+		if (detect_old_inaccurate_palette()) {
+			upgrade_old_inaccurate_palette();
+		}
+		
 		$G.triggerHandler("session-update"); // autosave
 		$G.triggerHandler("history-update"); // update history view
 
@@ -2031,7 +2036,7 @@ function detect_transparency(){
 	transparency = has_any_transparency(ctx);
 }
 
-function is_all_black_and_white(ctx) { 
+function is_all_black_and_white(ctx) {
 	const id = ctx.getImageData(0, 0, canvas.width, canvas.height);
 	for(let i=0, l=id.data.length; i<l; i+=4){
 		if(id.data[i+3] < 255){
@@ -2047,6 +2052,60 @@ function is_all_black_and_white(ctx) {
 	return true;
 }
 
+function detect_old_inaccurate_palette() {
+	let accurate_count = 0;
+	let inaccurate_count = 0;
+	const id = ctx.getImageData(0, 0, canvas.width, canvas.height);
+	for(let i=0, l=id.data.length; i<l; i+=4){
+		if (id.data[i+3] === 255) { // only count opaque pixels
+			for (const accurate_rgba of accurate_palette_rgbas) {
+				if (
+					id.data[i] === accurate_rgba[0] &&
+					id.data[i+1] === accurate_rgba[1] &&
+					id.data[i+2] === accurate_rgba[2]
+				) {
+					accurate_count++;
+				}
+			}
+			for (const inaccurate_rgba of inaccurate_palette_rgbas) {
+				if (
+					id.data[i] === inaccurate_rgba[0] &&
+					id.data[i+1] === inaccurate_rgba[1] &&
+					id.data[i+2] === inaccurate_rgba[2]
+				) {
+					inaccurate_count++;
+				}
+			}
+		}
+	}
+	// console.log({accurate_count, inaccurate_count, ratio: (inaccurate_count / accurate_count)});
+	return (inaccurate_count / accurate_count) > 1.2 && inaccurate_count > 0;
+}
+function upgrade_old_inaccurate_palette() {
+	const id = ctx.getImageData(0, 0, canvas.width, canvas.height);
+	for(let i=0, l=id.data.length; i<l; i+=4){
+		if (id.data[i+3] === 255) { // only upgrade opaque pixels
+			for (let j = 0; j < inaccurate_palette_rgbas.length; j++) {
+				if (
+					id.data[i] === inaccurate_palette_rgbas[j][0] &&
+					id.data[i+1] === inaccurate_palette_rgbas[j][1] &&
+					id.data[i+2] === inaccurate_palette_rgbas[j][2]
+				) {
+					id.data[i] = accurate_palette_rgbas[j][0];
+					id.data[i+1] = accurate_palette_rgbas[j][1];
+					id.data[i+2] = accurate_palette_rgbas[j][2];
+				}
+			}
+		}
+	}
+	undoable({
+		name: "Upgrade Inaccurate Palette",
+		icon: get_help_folder_icon("p_monochrome_undo.png"),
+	}, ()=> {
+		ctx.putImageData(id, 0, 0);
+	});
+}
+
 function make_monochrome_pattern(lightness){
 
 	const dither_threshold_table = Array.from({length: 64}, (_undefined, p) => {