diff --git a/src/error.rs b/src/error.rs
index 1adaa8e..4637b08 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -21,6 +21,12 @@ impl fmt::Display for NotFound {
     }
 }
 
+#[derive(Debug)]
+pub enum ImageError {
+    MalformedPixel,
+    WrongSize,
+}
+
 #[derive(Debug)]
 pub enum Error {
     Colour,
@@ -31,7 +37,9 @@ pub enum Error {
     Game {
         missing: NotFound,
     },
-    Image,
+    Image {
+        err: ImageError,
+    },
     Item,
     Palette,
     Position,
diff --git a/src/image.rs b/src/image.rs
index d202f37..4585842 100644
--- a/src/image.rs
+++ b/src/image.rs
@@ -1,4 +1,5 @@
 use std::fmt;
+use crate::error::ImageError;
 
 #[derive(Clone, Debug, Eq, PartialEq)]
 pub struct Image {
@@ -56,7 +57,7 @@ impl Image {
         let mut warnings = Vec::new();
 
         if str.contains("NaN") {
-            warnings.push(crate::Error::Image);
+            warnings.push(crate::Error::Image { err: ImageError::MalformedPixel });
         }
 
         let string = str.trim().replace("NaN", "0");
@@ -68,15 +69,24 @@ impl Image {
         for line in lines {
             let line = &line[..dimension];
             for char in line.chars().into_iter() {
-                // todo push warning on integers other than 0/1
-                pixels.push(match char {'1' => 1, _ => 0});
+                pixels.push(match char {
+                    '0' => 0,
+                    '1' => 1,
+                    _ => {
+                        warnings.push(
+                            crate::Error::Image { err: ImageError::MalformedPixel }
+                        );
+                        0
+                    }
+                });
             }
         }
 
+        // 8×8 (normal) or 16×16 (Bitsy HD)
         if [64, 256].contains(&pixels.len()) {
             Ok((Image { pixels }, warnings))
         } else {
-            Err(crate::Error::Image)
+            Err(crate::Error::Image { err: ImageError::WrongSize })
         }
     }
 }