diff --git a/src/cli/defines.rs b/src/cli/defines.rs
index 4d07f20..6e2213a 100644
--- a/src/cli/defines.rs
+++ b/src/cli/defines.rs
@@ -7,6 +7,7 @@ use pigment64::{ImageSize, ImageType};
 pub enum BinaryFormat {
     Ci4,
     Ci8,
+    I1,
     I4,
     I8,
     Ia4,
@@ -22,6 +23,7 @@ impl BinaryFormat {
         match self {
             BinaryFormat::Ci4 => CArrayWidth::U8,
             BinaryFormat::Ci8 => CArrayWidth::U8,
+            BinaryFormat::I1 => CArrayWidth::U8,
             BinaryFormat::I4 => CArrayWidth::U8,
             BinaryFormat::I8 => CArrayWidth::U8,
             BinaryFormat::Ia4 => CArrayWidth::U8,
@@ -37,6 +39,7 @@ impl BinaryFormat {
         match self {
             BinaryFormat::Ci4 => ImageType::Ci4,
             BinaryFormat::Ci8 => ImageType::Ci8,
+            BinaryFormat::I1 => ImageType::I1,
             BinaryFormat::I4 => ImageType::I4,
             BinaryFormat::I8 => ImageType::I8,
             BinaryFormat::Ia4 => ImageType::Ia4,
@@ -52,6 +55,7 @@ impl BinaryFormat {
         match self {
             BinaryFormat::Ci4 => Bits4,
             BinaryFormat::Ci8 => ImageSize::Bits8,
+            BinaryFormat::I1 => ImageSize::Bits1,
             BinaryFormat::I4 => ImageSize::Bits4,
             BinaryFormat::I8 => ImageSize::Bits8,
             BinaryFormat::Ia4 => ImageSize::Bits4,
diff --git a/src/image/native_image.rs b/src/image/native_image.rs
index ae16342..3abd741 100644
--- a/src/image/native_image.rs
+++ b/src/image/native_image.rs
@@ -34,6 +34,19 @@ impl NativeImage {
         let mut cursor = Cursor::new(&self.data);
 
         match self.format {
+            ImageType::I1 => {
+                for _y in 0..self.height {
+                    for _x in (0..self.width).step_by(8) {
+                        let byte = cursor.read_u8()?;
+
+                        for i in 0..8 {
+                            let mask = 0b00000001 << (7 - i);
+                            let intensity = if byte & mask == 0 { 0 } else { 255 };
+                            writer.write_all(&[intensity, intensity, intensity, 0xFF])?;
+                        }
+                    }
+                }
+            }
             ImageType::I4 => {
                 for _y in 0..self.height {
                     for _x in (0..self.width).step_by(2) {
@@ -149,19 +162,12 @@ impl NativeImage {
         let mut encoder = png::Encoder::new(writer, self.width, self.height);
 
         match self.format {
-            ImageType::I4 => {
-                self.decode(&mut data, None)?;
-            }
-            ImageType::I8 => {
-                self.decode(&mut data, None)?;
-            }
-            ImageType::Ia4 => {
-                self.decode(&mut data, None)?;
-            }
-            ImageType::Ia8 => {
-                self.decode(&mut data, None)?;
-            }
-            ImageType::Ia16 => {
+            ImageType::I1
+            | ImageType::I4
+            | ImageType::I8
+            | ImageType::Ia4
+            | ImageType::Ia8
+            | ImageType::Ia16 => {
                 self.decode(&mut data, None)?;
             }
             ImageType::Ci4 => {
diff --git a/src/image/png_image.rs b/src/image/png_image.rs
index 7eab89e..e049899 100644
--- a/src/image/png_image.rs
+++ b/src/image/png_image.rs
@@ -107,6 +107,7 @@ impl PNGImage {
 
     pub fn as_native<W: Write>(&self, writer: &mut W, image_type: ImageType) -> Result<()> {
         match image_type {
+            ImageType::I1 => self.as_i1(writer),
             ImageType::I4 => self.as_i4(writer),
             ImageType::I8 => self.as_i8(writer),
             ImageType::Ia4 => self.as_ia4(writer),
@@ -142,6 +143,25 @@ impl PNGImage {
         Ok(())
     }
 
+    pub fn as_i1<W: Write>(&self, writer: &mut W) -> Result<()> {
+        if let (ColorType::Grayscale, BitDepth::One) = (self.color_type, self.bit_depth) {
+            writer.write_all(&self.data).map_err(Into::into)
+        } else {
+            let mut i8_data = vec![0; self.data.len() * 8];
+            self.as_i8(&mut i8_data.as_mut_slice())?;
+
+            for chunk in i8_data.chunks_exact(8) {
+                let mut byte = 0;
+                for (i, pixel) in chunk.iter().copied().enumerate() {
+                    byte |= ((pixel > 127) as u8) << (7 - i);
+                }
+                writer.write_u8(byte)?;
+            }
+
+            Ok(())
+        }
+    }
+
     pub fn as_i4<W: Write>(&self, writer: &mut W) -> Result<()> {
         match (self.color_type, self.bit_depth) {
             (ColorType::Grayscale, BitDepth::Four) => writer.write_all(&self.data)?,
diff --git a/src/lib.rs b/src/lib.rs
index c79d290..2a80896 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -16,12 +16,14 @@ pub enum ImageSize {
     Bits8 = 1,
     Bits16 = 2,
     Bits32 = 3,
+    Bits1 = 4,
     DD = 5,
 }
 
 impl ImageSize {
     pub fn get_tlut_size(&self) -> usize {
         match self {
+            ImageSize::Bits1 => 0b10,
             ImageSize::Bits4 => 0x10,
             ImageSize::Bits8 => 0x100,
             ImageSize::Bits16 => 0x1000,
@@ -44,6 +46,7 @@ pub enum ImageFormat {
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TryFromPrimitive)]
 #[repr(u8)]
 pub enum ImageType {
+    I1,
     I4,
     I8,
     Ia4,
@@ -60,6 +63,7 @@ impl ImageType {
         match self {
             ImageType::Ci4 => ImageSize::Bits4,
             ImageType::Ci8 => ImageSize::Bits8,
+            ImageType::I1 => ImageSize::Bits1,
             ImageType::I4 => ImageSize::Bits4,
             ImageType::I8 => ImageSize::Bits8,
             ImageType::Ia4 => ImageSize::Bits4,
@@ -74,6 +78,7 @@ impl ImageType {
         match self {
             ImageType::Ci4 => ImageFormat::Ci,
             ImageType::Ci8 => ImageFormat::Ci,
+            ImageType::I1 => ImageFormat::I,
             ImageType::I4 => ImageFormat::I,
             ImageType::I8 => ImageFormat::I,
             ImageType::Ia4 => ImageFormat::Ia,