diff --git a/src/scene/view/render.rs b/src/scene/view/render.rs
index e2e4d301b..c1e80b531 100644
--- a/src/scene/view/render.rs
+++ b/src/scene/view/render.rs
@@ -3009,11 +3009,13 @@ impl Scene {
                         background.use_tiling as u8 as f32,
                         image.width as f32 / image.height.max(1) as f32,
                     ];
+                    // Offset, then the image's size in pixels at its scale:
+                    // an image not fitted to the screen keeps its pixel size.
                     result.image_transform = [
                         background.offset.x as f32,
                         background.offset.y as f32,
-                        background.scale.x as f32,
-                        background.scale.y as f32,
+                        background.scale.x as f32 * image.width as f32,
+                        background.scale.y as f32 * image.height as f32,
                     ];
                     result.params[0] = 4.0;
                     result.image = Some(image);
diff --git a/src/shaders/background.wgsl b/src/shaders/background.wgsl
index c99da6201..25a004c50 100644
--- a/src/shaders/background.wgsl
+++ b/src/shaders/background.wgsl
@@ -81,8 +81,12 @@ fn equirect_uv(ndc: vec2<f32>, rotation: f32) -> vec2<f32> {
 fn image_uv(source_uv: vec2<f32>) -> vec2<f32> {
     var uv = source_uv;
     if u.background_image_params.x < 0.5 {
-        uv = (source_uv - u.background_image_transform.xy)
-            / max(abs(u.background_image_transform.zw), vec2<f32>(1e-6));
+        // Not fitted: the image at its own pixel size (times its scale),
+        // centred on the viewport and moved by its offset.
+        let pixel = (source_uv - vec2<f32>(0.5)) * max(u.viewport_size, vec2<f32>(1.0));
+        uv = pixel / max(abs(u.background_image_transform.zw), vec2<f32>(1e-6))
+            + vec2<f32>(0.5) - u.background_image_transform.xy;
+        return select(uv, fract(uv), u.background_image_params.z > 0.5);
     }
     if u.background_image_params.y > 0.5 {
         let image_aspect = max(u.background_image_params.w, 1e-6);