diff --git a/poptimal.js b/poptimal.js
index 7a2f1a7..ff2a093 100644
--- a/poptimal.js
+++ b/poptimal.js
@@ -11,13 +11,14 @@ const xmlns = "http://www.w3.org/2000/xmlns/";
 const xlinkns = "http://www.w3.org/1999/xlink";
 const svgns = "http://www.w3.org/2000/svg";
 
-import {RADIUS_OPTS, DotMaker} from './src/components/dots.js';
+import {RADIUS_OPTS, RADIUS_DESC, DotMaker} from './src/components/dots.js';
 import {PALETTES, ColourNamer} from './src/components/palettes.js';
 
 const CELL = 10;
 const MAG = 2;
 const WIDTH = 20;
 const HEIGHT = WIDTH;
+const VISIBLE_DOG = 1000;
 
 function randomise_params() {
 	const palette_name = random.choice(Array.from(PALETTES.keys()));
@@ -52,29 +53,54 @@ async function get_histogram(imgfile) {
 
 
 function parse_histogram(convert_out) {
-	const colour_re = /(\d+): \(\d+,\d+,\d+,\d+\) #([A-F0-9]+) /;
+	const colour_re = /(\d+): \(\d+,\d+,\d+,\d+\) (#[A-F0-9]+) /;
 	const colours = new Map();
 	convert_out.split("\n").forEach((l) => {
 		const m = l.match(colour_re);
 		if( m ) {
-			console.log(m[1], m[2]);
-			const colour = m[2].substring(0, 6);
+			const colour = m[2].substring(0, 7);
 			colours.set(colour, Number(m[1]));
-		} else {
-			console.log(`no match ${l}`);
 		}
 	});
 	return new Map([...colours].sort((a, b) => b[1] - a[1]));
 }
 
 
+function colour_visible(hist, colour) {
+	const hexcolour = colour.formatHex().toUpperCase();
+	console.log(colour, hexcolour, hist.get(hexcolour));
+	return hist.get(hexcolour) > VISIBLE_DOG;
+}
 
-function image_description(namer, params) {
-	const bgc = namer.colour_to_text(params.background);
-	const dotc = params.patterns.map((p) => namer.colour_to_text(p.colour));
-	const a = bgc.match(/^[aeiou]/) ? 'an' : 'a';
-	return `A pattern of ${dotc[0]} and ${dotc[1]} dots on ${a} ${bgc} background`;
 
+function image_description(namer, params, histogram) {
+	const colours = [
+		params.background,
+		params.patterns[0].colour,
+		params.patterns[1].colour,
+	];
+	const i_vis = [0, 1, 2].filter((i) => colour_visible(histogram, colours[i]));
+	const named_colours = i_vis.map((i) => namer.colour_to_text(colours[i]));
+	const gradients = i_vis.map((i) => {
+		if( i > 0 ) {
+			return RADIUS_DESC[params.patterns[i - 1].f];
+		} else {
+			return '';
+		}
+	});
+	if( named_colours.length == 1 ) {
+		return `A solid field of ${named_colours[0]}`;
+	}
+	if( named_colours.length > 1 ) {
+		const bgc = named_colours[0];
+		const a = bgc.match(/^[aeiou]/) ? 'an' : 'a';
+		const dot_desc = named_colours.slice(1);
+		const gs = gradients.slice(1);
+		const pattern_desc = dot_desc.map((d, i) => `${d} dots ${gs[i]}`); 
+		const patterns = pattern_desc.join(' and ');
+		return `A pattern of ${patterns} on ${a} ${bgc} background`;
+	}
+	return "";
 }
 
 
@@ -154,21 +180,6 @@ async function post_image(image, alt_text, cf) {
 
 }
 
-function survey_pixels(pngData) {
-	const pixbuf = pngData.pixels;
-	const pixels = Array.from(pixbuf);
-	const colours = {};
-	for( let i = 0; i += 3; i < pixels.length ) {
-		const hex = `${pixels[i]},${pixels[i + 1]},${pixels[i + 2]}`;
-		if( ! hex in colours ) {
-			colours[hex] = 0;
-		} 
-		colours[hex]++;
-	}
-	console.log(colours);
-
-}
-
 
 async function main() {
 	const argv = yargs(hideBin(process.argv))
@@ -186,7 +197,6 @@ async function main() {
   	const imgfile = cf['working_dir'] + '/' + fn;
 
 	const params = randomise_params();
-	console.log(params.palette);
 	const colourf = params.palette === 'grayscale' ? cf['grayscale'] : cf['colour'];
 
 	const namer = new ColourNamer();
@@ -212,11 +222,10 @@ async function main() {
   	// generate the alt_text last to check the image file histogram
   	// so we don't include obscured colours
   	const hist = await get_histogram(imgfile);
-  	console.log(hist);
-	const alt_text = image_description(namer, params, imgfile);
+	const alt_text = image_description(namer, params, hist);
 
-	console.log(imgfile);
 	console.log(alt_text);
+	console.log(imgfile);
   	if( cf['base_url'] ) {
   		await post_image(imgfile, alt_text, cf);
   	}
diff --git a/src/components/dots.js b/src/components/dots.js
index 03d2e9e..d767b6a 100644
--- a/src/components/dots.js
+++ b/src/components/dots.js
@@ -16,6 +16,21 @@ const RADIUS_OPTS = [
 	"noise",
 ];
 
+const RADIUS_DESC = {
+	"const": "of constant size",
+	"right": "getting larger towards the left",
+	"left": "getting larger towards the left",
+	"up": "getting larger towards the top",
+	"down": "getting larger towards the bottom",
+	"right-up": "getting larger towards the upper right",
+	"right-down": "getting larger towards the lower right",
+	"left-up": "getting larger towards the upper left",
+	"left-down": "getting larger towards the lower left",
+	"in": "getting larger in the centre",
+	"out": "getting larger at the edges",
+	"noise": "of random sizes",
+}
+
 function distance(dx, dy) {
 	return Math.sqrt(dx ** 2 + dy ** 2);
 }
@@ -92,6 +107,6 @@ class DotMaker {
 	}
 }
 
-export { RADIUS_OPTS, DotMaker };
+export { RADIUS_OPTS, RADIUS_DESC, DotMaker };