diff --git a/draftlogs/6712_add.md b/draftlogs/6712_add.md
new file mode 100644
index 00000000000..ac47acf1823
--- /dev/null
+++ b/draftlogs/6712_add.md
@@ -0,0 +1 @@
+- Allow to remove a scaleanchor constraint that is set by default [[#6712](https://github.com/plotly/plotly.js/pull/6712)], with thanks to @lvlte for the contribution!
diff --git a/src/plots/cartesian/constraints.js b/src/plots/cartesian/constraints.js
index 27596ff4eb9..d825cd92e3e 100644
--- a/src/plots/cartesian/constraints.js
+++ b/src/plots/cartesian/constraints.js
@@ -253,7 +253,7 @@ function handleOneAxDefaults(axIn, axOut, opts) {
         scaleanchor = Lib.coerce(axIn, axOut, {
             scaleanchor: {
                 valType: 'enumerated',
-                values: linkableAxes
+                values: linkableAxes.concat([false])
             }
         }, 'scaleanchor', scaleanchorDflt);
     }
diff --git a/src/plots/cartesian/layout_attributes.js b/src/plots/cartesian/layout_attributes.js
index 94cc77d9d9f..b3854603116 100644
--- a/src/plots/cartesian/layout_attributes.js
+++ b/src/plots/cartesian/layout_attributes.js
@@ -330,12 +330,13 @@ module.exports = {
         ].join(' ')
     },
     // scaleanchor: not used directly, just put here for reference
-    // values are any opposite-letter axis id
+    // values are any opposite-letter axis id, or `false`.
     scaleanchor: {
         valType: 'enumerated',
         values: [
             constants.idRegex.x.toString(),
-            constants.idRegex.y.toString()
+            constants.idRegex.y.toString(),
+            false
         ],
         editType: 'plot',
         description: [
@@ -353,7 +354,12 @@ module.exports = {
             'and the last constraint encountered will be ignored to avoid possible',
             'inconsistent constraints via `scaleratio`.',
             'Note that setting axes simultaneously in both a `scaleanchor` and a `matches` constraint',
-            'is currently forbidden.'
+            'is currently forbidden.',
+            'Setting `false` allows to remove a default constraint (occasionally,',
+            'you may need to prevent a default `scaleanchor` constraint from',
+            'being applied, eg. when having an image trace `yaxis: {scaleanchor: "x"}`',
+            'is set automatically in order for pixels to be rendered as squares,',
+            'setting `yaxis: {scaleanchor: false}` allows to remove the constraint).'
         ].join(' ')
     },
     scaleratio: {
diff --git a/test/jasmine/tests/image_test.js b/test/jasmine/tests/image_test.js
index a5fe6fd4a77..81fa1d28105 100644
--- a/test/jasmine/tests/image_test.js
+++ b/test/jasmine/tests/image_test.js
@@ -209,6 +209,14 @@ describe('image smart layout defaults', function() {
         expect(gd._fullLayout.yaxis.scaleanchor).toBe('x');
     });
 
+    it('should NOT set scaleanchor if asked not to', function() {
+        gd = {};
+        gd.data = [{type: 'image', z: [[[255, 0, 0]]]}];
+        gd.layout = {yaxis: {scaleanchor: false}};
+        supplyAllDefaults(gd);
+        expect(gd._fullLayout.yaxis.scaleanchor).toBe(false);
+    });
+
     it('should NOT reset scaleanchor if it\'s already defined', function() {
         gd.data = [{type: 'image', z: [[[255, 0, 0]]]}, {y: [5, 3, 2], xaxis: 'x3'}];
         gd.layout = {yaxis: {scaleanchor: 'x3'}};
diff --git a/test/plot-schema.json b/test/plot-schema.json
index 8e8dcb0356c..6a1f962255c 100644
--- a/test/plot-schema.json
+++ b/test/plot-schema.json
@@ -11157,12 +11157,13 @@
     },
     "role": "object",
     "scaleanchor": {
-     "description": "If set to another axis id (e.g. `x2`, `y`), the range of this axis changes together with the range of the corresponding axis such that the scale of pixels per unit is in a constant ratio. Both axes are still zoomable, but when you zoom one, the other will zoom the same amount, keeping a fixed midpoint. `constrain` and `constraintoward` determine how we enforce the constraint. You can chain these, ie `yaxis: {scaleanchor: *x*}, xaxis2: {scaleanchor: *y*}` but you can only link axes of the same `type`. The linked axis can have the opposite letter (to constrain the aspect ratio) or the same letter (to match scales across subplots). Loops (`yaxis: {scaleanchor: *x*}, xaxis: {scaleanchor: *y*}` or longer) are redundant and the last constraint encountered will be ignored to avoid possible inconsistent constraints via `scaleratio`. Note that setting axes simultaneously in both a `scaleanchor` and a `matches` constraint is currently forbidden.",
+     "description": "If set to another axis id (e.g. `x2`, `y`), the range of this axis changes together with the range of the corresponding axis such that the scale of pixels per unit is in a constant ratio. Both axes are still zoomable, but when you zoom one, the other will zoom the same amount, keeping a fixed midpoint. `constrain` and `constraintoward` determine how we enforce the constraint. You can chain these, ie `yaxis: {scaleanchor: *x*}, xaxis2: {scaleanchor: *y*}` but you can only link axes of the same `type`. The linked axis can have the opposite letter (to constrain the aspect ratio) or the same letter (to match scales across subplots). Loops (`yaxis: {scaleanchor: *x*}, xaxis: {scaleanchor: *y*}` or longer) are redundant and the last constraint encountered will be ignored to avoid possible inconsistent constraints via `scaleratio`. Note that setting axes simultaneously in both a `scaleanchor` and a `matches` constraint is currently forbidden. Setting `false` allows to remove a default constraint (occasionally, you may need to prevent a default `scaleanchor` constraint from being applied, eg. when having an image trace `yaxis: {scaleanchor: \"x\"}` is set automatically in order for pixels to be rendered as squares, setting `yaxis: {scaleanchor: false}` allows to remove the constraint).",
      "editType": "plot",
      "valType": "enumerated",
      "values": [
       "/^x([2-9]|[1-9][0-9]+)?( domain)?$/",
-      "/^y([2-9]|[1-9][0-9]+)?( domain)?$/"
+      "/^y([2-9]|[1-9][0-9]+)?( domain)?$/",
+      false
      ]
     },
     "scaleratio": {
@@ -12167,12 +12168,13 @@
     },
     "role": "object",
     "scaleanchor": {
-     "description": "If set to another axis id (e.g. `x2`, `y`), the range of this axis changes together with the range of the corresponding axis such that the scale of pixels per unit is in a constant ratio. Both axes are still zoomable, but when you zoom one, the other will zoom the same amount, keeping a fixed midpoint. `constrain` and `constraintoward` determine how we enforce the constraint. You can chain these, ie `yaxis: {scaleanchor: *x*}, xaxis2: {scaleanchor: *y*}` but you can only link axes of the same `type`. The linked axis can have the opposite letter (to constrain the aspect ratio) or the same letter (to match scales across subplots). Loops (`yaxis: {scaleanchor: *x*}, xaxis: {scaleanchor: *y*}` or longer) are redundant and the last constraint encountered will be ignored to avoid possible inconsistent constraints via `scaleratio`. Note that setting axes simultaneously in both a `scaleanchor` and a `matches` constraint is currently forbidden.",
+     "description": "If set to another axis id (e.g. `x2`, `y`), the range of this axis changes together with the range of the corresponding axis such that the scale of pixels per unit is in a constant ratio. Both axes are still zoomable, but when you zoom one, the other will zoom the same amount, keeping a fixed midpoint. `constrain` and `constraintoward` determine how we enforce the constraint. You can chain these, ie `yaxis: {scaleanchor: *x*}, xaxis2: {scaleanchor: *y*}` but you can only link axes of the same `type`. The linked axis can have the opposite letter (to constrain the aspect ratio) or the same letter (to match scales across subplots). Loops (`yaxis: {scaleanchor: *x*}, xaxis: {scaleanchor: *y*}` or longer) are redundant and the last constraint encountered will be ignored to avoid possible inconsistent constraints via `scaleratio`. Note that setting axes simultaneously in both a `scaleanchor` and a `matches` constraint is currently forbidden. Setting `false` allows to remove a default constraint (occasionally, you may need to prevent a default `scaleanchor` constraint from being applied, eg. when having an image trace `yaxis: {scaleanchor: \"x\"}` is set automatically in order for pixels to be rendered as squares, setting `yaxis: {scaleanchor: false}` allows to remove the constraint).",
      "editType": "plot",
      "valType": "enumerated",
      "values": [
       "/^x([2-9]|[1-9][0-9]+)?( domain)?$/",
-      "/^y([2-9]|[1-9][0-9]+)?( domain)?$/"
+      "/^y([2-9]|[1-9][0-9]+)?( domain)?$/",
+      false
      ]
     },
     "scaleratio": {