diff --git a/libsquoosh/README.md b/libsquoosh/README.md
index 3c11e010..af8c9a93 100644
--- a/libsquoosh/README.md
+++ b/libsquoosh/README.md
@@ -42,11 +42,19 @@ When an image has been ingested, you can start preprocessing it and encoding it
 await image.decoded; //Wait until the image is decoded before running preprocessors. 
 
 const preprocessOptions = {
+  //When both width and height are specified, the image resized to specified size.
   resize: {
     enabled: true,
     width: 100,
     height: 50,
   }
+  /*
+  //When either width or height is specified, the image resized to specified size keeping aspect ratio.
+  resize: {
+    enabled: true,
+    width: 100,
+  }
+  */
 }
 await image.preprocess(preprocessOptions);
 
diff --git a/libsquoosh/src/auto-optimizer.js b/libsquoosh/src/auto-optimizer.ts
similarity index 54%
rename from libsquoosh/src/auto-optimizer.js
rename to libsquoosh/src/auto-optimizer.ts
index 1c536a3d..bffa4dc3 100644
--- a/libsquoosh/src/auto-optimizer.js
+++ b/libsquoosh/src/auto-optimizer.ts
@@ -2,6 +2,39 @@ import { instantiateEmscriptenWasm } from './emscripten-utils.js';
 
 import visdif from '../../codecs/visdif/visdif.js';
 import visdifWasm from 'asset-url:../../codecs/visdif/visdif.wasm';
+import type ImageData from './image_data';
+
+interface VisDiff {
+  distance: (data: Uint8ClampedArray) => number;
+  delete: () => void;
+}
+
+interface VisdiffConstructor {
+  new (data: Uint8ClampedArray, width: number, height: number): VisDiff;
+}
+
+interface VisDiffModule extends EmscriptenWasm.Module {
+  VisDiff: VisdiffConstructor;
+}
+
+type VisDiffModuleFactory = EmscriptenWasm.ModuleFactory<VisDiffModule>;
+
+interface BinarySearchParams {
+  min?: number;
+  max?: number;
+  epsilon?: number;
+  maxRounds?: number;
+}
+
+interface AutoOptimizeParams extends BinarySearchParams {
+  butteraugliDistanceGoal?: number;
+}
+
+interface AutoOptimizeResult {
+  bitmap: ImageData;
+  binary: Uint8Array;
+  quality: number;
+}
 
 // `measure` is a (async) function that takes exactly one numeric parameter and
 // returns a value. The function is assumed to be monotonic (an increase in `parameter`
@@ -9,9 +42,9 @@ import visdifWasm from 'asset-url:../../codecs/visdif/visdif.wasm';
 // to find `parameter` such that `measure` returns `measureGoal`, within an error
 // of `epsilon`. It will use at most `maxRounds` attempts.
 export async function binarySearch(
-  measureGoal,
-  measure,
-  { min = 0, max = 100, epsilon = 0.1, maxRounds = 6 } = {},
+  measureGoal: number,
+  measure: (val: number) => Promise<number>,
+  { min = 0, max = 100, epsilon = 0.1, maxRounds = 6 }: BinarySearchParams = {},
 ) {
   let parameter = (max - min) / 2 + min;
   let delta = (max - min) / 4;
@@ -33,12 +66,21 @@ export async function binarySearch(
 }
 
 export async function autoOptimize(
-  bitmapIn,
-  encode,
-  decode,
-  { butteraugliDistanceGoal = 1.4, ...otherOpts } = {},
-) {
-  const { VisDiff } = await instantiateEmscriptenWasm(visdif, visdifWasm);
+  bitmapIn: ImageData,
+  encode: (
+    bitmap: ImageData,
+    quality: number,
+  ) => Promise<Uint8Array> | Uint8Array,
+  decode: (binary: Uint8Array) => Promise<ImageData> | ImageData,
+  {
+    butteraugliDistanceGoal = 1.4,
+    ...binarySearchParams
+  }: AutoOptimizeParams = {},
+): Promise<AutoOptimizeResult> {
+  const { VisDiff } = await instantiateEmscriptenWasm(
+    visdif as VisDiffModuleFactory,
+    visdifWasm,
+  );
 
   const comparator = new VisDiff(
     bitmapIn.data,
@@ -46,8 +88,11 @@ export async function autoOptimize(
     bitmapIn.height,
   );
 
-  let bitmapOut;
-  let binaryOut;
+  // We're able to do non null assertion because
+  // we know that binarySearch will set these values
+  let bitmapOut!: ImageData;
+  let binaryOut!: Uint8Array;
+
   // Increasing quality means _decrease_ in Butteraugli distance.
   // `binarySearch` assumes that increasing `parameter` will
   // increase the metric value. So multipliy Butteraugli values by -1.
@@ -58,7 +103,7 @@ export async function autoOptimize(
       bitmapOut = await decode(binaryOut);
       return -1 * comparator.distance(bitmapOut.data);
     },
-    otherOpts,
+    binarySearchParams,
   );
   comparator.delete();
 
diff --git a/src/client/lazy-app/Compress/Options/Range/index.tsx b/src/client/lazy-app/Compress/Options/Range/index.tsx
index da6e37e2..8b1150e3 100644
--- a/src/client/lazy-app/Compress/Options/Range/index.tsx
+++ b/src/client/lazy-app/Compress/Options/Range/index.tsx
@@ -6,10 +6,13 @@ import './custom-els/RangeInput';
 import { linkRef } from 'shared/prerendered-app/util';
 
 interface Props extends preact.JSX.HTMLAttributes {}
-interface State {}
+interface State {
+  textFocused: boolean;
+}
 
 export default class Range extends Component<Props, State> {
   rangeWc?: RangeInputElement;
+  inputEl?: HTMLInputElement;
 
   private onTextInput = (event: Event) => {
     const input = event.target as HTMLInputElement;
@@ -23,10 +26,19 @@ export default class Range extends Component<Props, State> {
     );
   };
 
-  render(props: Props) {
+  private onTextFocus = () => {
+    this.setState({ textFocused: true });
+  };
+
+  private onTextBlur = () => {
+    this.setState({ textFocused: false });
+  };
+
+  render(props: Props, state: State) {
     const { children, ...otherProps } = props;
 
     const { value, min, max, step } = props;
+    const textValue = state.textFocused ? this.inputEl!.value : value;
 
     return (
       <label class={style.range}>
@@ -41,13 +53,16 @@ export default class Range extends Component<Props, State> {
           />
         </div>
         <input
+          ref={linkRef(this, 'inputEl')}
           type="number"
           class={style.textInput}
-          value={value}
+          value={textValue}
           min={min}
           max={max}
           step={step}
           onInput={this.onTextInput}
+          onFocus={this.onTextFocus}
+          onBlur={this.onTextBlur}
         />
       </label>
     );