diff --git a/addons/web_editor/static/src/js/editor/image_processing.js b/addons/web_editor/static/src/js/editor/image_processing.js
index 1f87360f9c4..8b66f16e6f6 100644
--- a/addons/web_editor/static/src/js/editor/image_processing.js
+++ b/addons/web_editor/static/src/js/editor/image_processing.js
@@ -334,7 +334,13 @@ async function applyModifications(img, dataOptions = {}) {
     ctx.fillRect(0, 0, result.width, result.height);
 
     // Quality
-    return result.toDataURL(mimetype, quality / 100);
+    const dataURL = result.toDataURL(mimetype, quality / 100);
+    const newSize = getDataURLBinarySize(dataURL);
+    const originalSize = _getImageSizeFromCache(originalSrc);
+    const isChanged = !!perspective || !!glFilter ||
+        original.width !== result.width || original.height !== result.height ||
+        original.width !== croppedImg.width || original.height !== croppedImg.height;
+    return (isChanged || originalSize >= newSize) ? dataURL : await _loadImageDataURL(originalSrc);
 }
 
 /**
@@ -391,9 +397,18 @@ async function _updateImageData(src, key = 'objectURL') {
     } else {
         value = URL.createObjectURL(blob);
     }
-    imageCache.set(src, Object.assign(currentImageData || {}, {[key]: value}));
+    imageCache.set(src, Object.assign(currentImageData || {}, {[key]: value, size: blob.size}));
     return value;
 }
+/**
+ * Returns the size of a cached image.
+ *
+ * @param {String} src used as a key on the image cache map.
+ * @returns {Number} size of the image in bytes.
+ */
+function _getImageSizeFromCache(src) {
+    return imageCache.get(src).size;
+}
 /**
  * Activates the cropper on a given image.
  *
diff --git a/addons/web_tour/static/src/tour_service/tour_utils.js b/addons/web_tour/static/src/tour_service/tour_utils.js
index 26a36e779b3..5d9db91ce1c 100644
--- a/addons/web_tour/static/src/tour_service/tour_utils.js
+++ b/addons/web_tour/static/src/tour_service/tour_utils.js
@@ -211,6 +211,9 @@ export class RunningTourActionHelper {
     text_blur(text, element) {
         this._text_blur(this._get_action_values(element), text);
     }
+    range(text, element) {
+        this._range(this._get_action_values(element), text);
+    }
     drag_and_drop(to, element) {
         this._drag_and_drop_jquery(this._get_action_values(element), to);
     }
@@ -313,6 +316,10 @@ export class RunningTourActionHelper {
         values.$element.trigger("focusout");
         values.$element.trigger("blur");
     }
+    _range(values, text) {
+        values.$element[0].value = text;
+        values.$element[0].dispatchEvent(new Event('change', { bubbles: true, cancelable: false }));
+    }
     _calculateCenter($el, selector) {
         const center = $el.offset();
         if (selector && selector.indexOf("iframe") !== -1) {
diff --git a/addons/website/static/tests/tours/snippet_image_quality.js b/addons/website/static/tests/tours/snippet_image_quality.js
new file mode 100644
index 00000000000..4f36c7e66e4
--- /dev/null
+++ b/addons/website/static/tests/tours/snippet_image_quality.js
@@ -0,0 +1,55 @@
+/** @odoo-module */
+
+import wTourUtils from 'website.tour_utils';
+
+wTourUtils.registerWebsitePreviewTour('website_image_quality', {
+    test: true,
+    url: '/',
+    edition: true,
+}, [
+    wTourUtils.dragNDrop({
+        id: 's_text_image',
+        name: 'Text - Image',
+    }),
+    {
+        content: "Select image",
+        trigger: 'iframe .s_text_image img',
+    },
+    {
+        content: "Set low quality",
+        trigger: 'we-customizeblock-options:has(we-title:contains("Image")) we-range[data-set-quality] input',
+        run: 'range 5',
+    },
+    {
+        content: "Wait for image update: NOT original image",
+        trigger: 'iframe .s_text_image img:not([src$="s_text_image_default_image"])',
+        run: () => {}, // It is a check.
+    },
+    {
+        content: "Check image size",
+        // Reached size cannot be hardcoded because it changes with
+        // different versions of Chrome.
+        trigger: 'we-customizeblock-options:has(we-title:contains("Image")) .o_we_image_weight:contains(" kb"):not(:contains("16.1 kb"))',
+        run() {
+            // Make sure the reached size is smaller than the original one.
+            if (parseFloat(this.$anchor[0].innerText) >= 47.5) {
+                console.error("Image size should be smaller than original");
+            }
+        },
+    },
+    {
+        content: "Set high quality",
+        trigger: 'we-customizeblock-options:has(we-title:contains("Image")) we-range[data-set-quality] input',
+        run: 'range 99',
+    },
+    {
+        content: "Wait for image update: back to original image",
+        trigger: 'iframe .s_text_image img[src$="QUntVvdqEdljipEUu7ez5lb6IqyGKzQmRxVnZX/2Q=="]',
+        run: () => {}, // It is a check.
+    },
+    {
+        content: "Check image size",
+        trigger: 'we-customizeblock-options:has(we-title:contains("Image")) .o_we_image_weight:contains("47.5 kb")',
+        run: () => {}, // It is a check.
+    },
+]);
diff --git a/addons/website/tests/test_attachment.py b/addons/website/tests/test_attachment.py
index 90d6844fa73..6070a7960be 100644
--- a/addons/website/tests/test_attachment.py
+++ b/addons/website/tests/test_attachment.py
@@ -1,3 +1,6 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
 from urllib.parse import urlparse
 
 import odoo.tests
@@ -51,3 +54,6 @@ class TestWebsiteAttachment(odoo.tests.HttpCase):
 
         req = self.opener.get(base + '/web/image/test.an_image_redirect_301', allow_redirects=True)
         self.assertEqual(req.status_code, 200)
+
+    def test_02_image_quality(self):
+        self.start_tour(self.env['website'].get_client_action_url('/'), 'website_image_quality', login="admin")
diff --git a/odoo/addons/base/tests/test_image.py b/odoo/addons/base/tests/test_image.py
index 7ef40bc2926..7df9974a825 100644
--- a/odoo/addons/base/tests/test_image.py
+++ b/odoo/addons/base/tests/test_image.py
@@ -177,6 +177,19 @@ class TestImage(TransactionCase):
         res = tools.image_process(self.img_1920x1080_jpeg)
         self.assertLessEqual(len(res), len(self.img_1920x1080_jpeg))
 
+        # CASE: JPEG optimize + bigger size => original
+        pil_image = Image.new('RGB', (1920, 1080), color=self.bg_color)
+        # Drawing non trivial content so that optimization matters.
+        ImageDraw.Draw(pil_image).ellipse(xy=[
+            (400, 0),
+            (1500, 1080)
+        ], fill=self.fill_color, outline=(240, 25, 40), width=10)
+        image = tools.image_apply_opt(pil_image, 'JPEG')
+        res = tools.image_process(image, quality=50)
+        self.assertLess(len(res), len(image), "Low quality image should be smaller than original")
+        res = tools.image_process(image, quality=99)
+        self.assertEqual(len(res), len(image), "Original should be returned if size increased")
+
         # CASE: GIF doesn't apply quality, just optimize
         image = tools.image_apply_opt(Image.new('RGB', (1080, 1920)), 'GIF')
         res = tools.image_process(image)
diff --git a/odoo/tools/image.py b/odoo/tools/image.py
index 9b8b4efda1b..ede32cd592c 100644
--- a/odoo/tools/image.py
+++ b/odoo/tools/image.py
@@ -151,7 +151,12 @@ class ImageProcess():
         if output_image.mode not in ["1", "L", "P", "RGB", "RGBA"] or (output_format == 'JPEG' and output_image.mode == 'RGBA'):
             output_image = output_image.convert("RGB")
 
-        return image_apply_opt(output_image, **opt)
+        output_bytes = image_apply_opt(output_image, **opt)
+        if len(output_bytes) >= len(self.source) and self.original_format == output_format and not self.operationsCount:
+            # Format has not changed and image content is unchanged but the
+            # reached binary is bigger: rather use the original.
+            return self.source
+        return output_bytes
 
     def resize(self, max_width=0, max_height=0):
         """Resize the image.