diff --git a/core/fpdfapi/page/cpdf_dib.cpp b/core/fpdfapi/page/cpdf_dib.cpp
index c478d37..657cf16 100644
--- a/core/fpdfapi/page/cpdf_dib.cpp
+++ b/core/fpdfapi/page/cpdf_dib.cpp
@@ -1132,11 +1132,6 @@
   return true;
 }
 
-pdfium::span<const uint8_t> CPDF_DIB::GetBuffer() const {
-  return m_pCachedBitmap ? m_pCachedBitmap->GetBuffer()
-                         : pdfium::span<const uint8_t>();
-}
-
 pdfium::span<const uint8_t> CPDF_DIB::GetScanline(int line) const {
   if (m_bpc == 0)
     return pdfium::span<const uint8_t>();
diff --git a/core/fpdfapi/page/cpdf_dib.h b/core/fpdfapi/page/cpdf_dib.h
index 5206bf5..1ef656a 100644
--- a/core/fpdfapi/page/cpdf_dib.h
+++ b/core/fpdfapi/page/cpdf_dib.h
@@ -45,7 +45,6 @@
   CONSTRUCT_VIA_MAKE_RETAIN;
 
   // CFX_DIBBase:
-  pdfium::span<const uint8_t> GetBuffer() const override;
   pdfium::span<const uint8_t> GetScanline(int line) const override;
   bool SkipToScanline(int line, PauseIndicatorIface* pPause) const override;
   size_t GetEstimatedImageMemoryBurden() const override;
diff --git a/core/fpdfapi/page/cpdf_pageimagecache.cpp b/core/fpdfapi/page/cpdf_pageimagecache.cpp
index b36f089..30d6aa1 100644
--- a/core/fpdfapi/page/cpdf_pageimagecache.cpp
+++ b/core/fpdfapi/page/cpdf_pageimagecache.cpp
@@ -28,7 +28,6 @@
 #if defined(_SKIA_SUPPORT_)
 #include "core/fxcrt/data_vector.h"
 #include "core/fxge/cfx_defaultrenderdevice.h"
-#include "third_party/base/notreached.h"
 #include "third_party/skia/include/core/SkImage.h"   // nogncheck
 #include "third_party/skia/include/core/SkRefCnt.h"  // nogncheck
 #endif
@@ -63,15 +62,6 @@
     }
   }
 
-  pdfium::span<const uint8_t> GetBuffer() const override {
-    // TODO(crbug.com/pdfium/2051): Still needed for
-    // CGdiDeviceDriver::GDI_StretchDIBits(). `CachedImage` is only used when
-    // Skia is the default renderer, which should call `RealizeSkImage()`
-    // instead. Consider removing this or making it `NOTREACHED_NORETURN()`
-    // by reimplementing its caller when Skia is the default renderer.
-    return image_->GetBuffer();
-  }
-
   pdfium::span<const uint8_t> GetScanline(int line) const override {
     // TODO(crbug.com/pdfium/2050): Still needed for `Realize()` call in
     // `CPDF_ImageRenderer`.
@@ -79,10 +69,6 @@
   }
 
   bool SkipToScanline(int line, PauseIndicatorIface* pause) const override {
-    // TODO(crbug.com/pdfium/2051): `CachedImage` is only used by Skia, which
-    // should call `RealizeSkImage()` instead. Consider removing this, or at
-    // least making it `NOTREACHED_NORETURN()`.
-    NOTREACHED();
     return image_->SkipToScanline(line, pause);
   }
 
@@ -91,6 +77,12 @@
     return image_->GetEstimatedImageMemoryBurden();
   }
 
+#if BUILDFLAG(IS_WIN) || defined(_SKIA_SUPPORT_)
+  RetainPtr<const CFX_DIBitmap> RealizeIfNeeded() const override {
+    return image_->RealizeIfNeeded();
+  }
+#endif
+
   sk_sp<SkImage> RealizeSkImage() const override {
     if (!cached_skia_image_) {
       cached_skia_image_ = image_->RealizeSkImage();
@@ -111,15 +103,7 @@
                                        bool realize_hint) {
 #if defined(_SKIA_SUPPORT_)
   if (CFX_DefaultRenderDevice::SkiaIsDefaultRenderer()) {
-    // TODO(crbug.com/pdfium/2050): Ignore `realize_hint`, as `RealizeSkImage()`
-    // doesn't benefit from it. The current behavior masks a bug in `CPDF_DIB`
-    // in which `GetBuffer()` and `GetScanline()` don't give the same answer.
-    if (realize_hint) {
-      image = image->Realize();
-      if (!image) {
-        return nullptr;
-      }
-    }
+    // Ignore `realize_hint`, as `RealizeSkImage()` doesn't benefit from it.
     return pdfium::MakeRetain<CachedImage>(std::move(image));
   }
 #endif  // defined(_SKIA_SUPPORT_)
diff --git a/core/fxge/dib/cfx_dibbase.cpp b/core/fxge/dib/cfx_dibbase.cpp
index 2a80f89..bf823dc 100644
--- a/core/fxge/dib/cfx_dibbase.cpp
+++ b/core/fxge/dib/cfx_dibbase.cpp
@@ -617,10 +617,6 @@
 
 CFX_DIBBase::~CFX_DIBBase() = default;
 
-pdfium::span<const uint8_t> CFX_DIBBase::GetBuffer() const {
-  return pdfium::span<const uint8_t>();
-}
-
 bool CFX_DIBBase::SkipToScanline(int line, PauseIndicatorIface* pPause) const {
   return false;
 }
@@ -629,12 +625,9 @@
   return GetRequiredPaletteSize() * sizeof(uint32_t);
 }
 
-#if BUILDFLAG(IS_WIN)
-RetainPtr<const CFX_DIBBase> CFX_DIBBase::RealizeIfNeeded() const {
-  if (GetBuffer().empty()) {
-    return Realize();
-  }
-  return pdfium::WrapRetain(this);
+#if BUILDFLAG(IS_WIN) || defined(_SKIA_SUPPORT_)
+RetainPtr<const CFX_DIBitmap> CFX_DIBBase::RealizeIfNeeded() const {
+  return Realize();
 }
 #endif
 
diff --git a/core/fxge/dib/cfx_dibbase.h b/core/fxge/dib/cfx_dibbase.h
index 6327888..98febad 100644
--- a/core/fxge/dib/cfx_dibbase.h
+++ b/core/fxge/dib/cfx_dibbase.h
@@ -41,10 +41,13 @@
 
   static constexpr uint32_t kPaletteSize = 256;
 
-  virtual pdfium::span<const uint8_t> GetBuffer() const;
   virtual pdfium::span<const uint8_t> GetScanline(int line) const = 0;
   virtual bool SkipToScanline(int line, PauseIndicatorIface* pPause) const;
   virtual size_t GetEstimatedImageMemoryBurden() const;
+#if BUILDFLAG(IS_WIN) || defined(_SKIA_SUPPORT_)
+  // Calls Realize() if needed. Otherwise, return `this`.
+  virtual RetainPtr<const CFX_DIBitmap> RealizeIfNeeded() const;
+#endif
 
   int GetWidth() const { return m_Width; }
   int GetHeight() const { return m_Height; }
@@ -65,11 +68,6 @@
   // Copies into internally-owned palette.
   void SetPalette(pdfium::span<const uint32_t> src_palette);
 
-#if BUILDFLAG(IS_WIN)
-  // Calls Realize() if needed. Otherwise, return `this`.
-  RetainPtr<const CFX_DIBBase> RealizeIfNeeded() const;
-#endif
-
   RetainPtr<CFX_DIBitmap> Realize() const;
   RetainPtr<CFX_DIBitmap> ClipTo(const FX_RECT& rect) const;
   RetainPtr<CFX_DIBitmap> ConvertTo(FXDIB_Format format) const;
diff --git a/core/fxge/dib/cfx_dibitmap.cpp b/core/fxge/dib/cfx_dibitmap.cpp
index 6df1eee..cf349c0 100644
--- a/core/fxge/dib/cfx_dibitmap.cpp
+++ b/core/fxge/dib/cfx_dibitmap.cpp
@@ -110,6 +110,15 @@
   return result;
 }
 
+#if BUILDFLAG(IS_WIN) || defined(_SKIA_SUPPORT_)
+RetainPtr<const CFX_DIBitmap> CFX_DIBitmap::RealizeIfNeeded() const {
+  if (GetBuffer().empty()) {
+    return Realize();
+  }
+  return pdfium::WrapRetain(this);
+}
+#endif
+
 void CFX_DIBitmap::TakeOver(RetainPtr<CFX_DIBitmap>&& pSrcBitmap) {
   m_pBuffer = std::move(pSrcBitmap->m_pBuffer);
   m_palette = std::move(pSrcBitmap->m_palette);
diff --git a/core/fxge/dib/cfx_dibitmap.h b/core/fxge/dib/cfx_dibitmap.h
index 34f5887..e59644d 100644
--- a/core/fxge/dib/cfx_dibitmap.h
+++ b/core/fxge/dib/cfx_dibitmap.h
@@ -34,10 +34,13 @@
   bool Copy(const RetainPtr<CFX_DIBBase>& pSrc);
 
   // CFX_DIBBase
-  pdfium::span<const uint8_t> GetBuffer() const override;
   pdfium::span<const uint8_t> GetScanline(int line) const override;
   size_t GetEstimatedImageMemoryBurden() const override;
+#if BUILDFLAG(IS_WIN) || defined(_SKIA_SUPPORT_)
+  RetainPtr<const CFX_DIBitmap> RealizeIfNeeded() const override;
+#endif
 
+  pdfium::span<const uint8_t> GetBuffer() const;
   pdfium::span<uint8_t> GetWritableBuffer() {
     pdfium::span<const uint8_t> src = GetBuffer();
     return {const_cast<uint8_t*>(src.data()), src.size()};
diff --git a/core/fxge/skia/cfx_dibbase_skia.cpp b/core/fxge/skia/cfx_dibbase_skia.cpp
index 417aa93..8606e33 100644
--- a/core/fxge/skia/cfx_dibbase_skia.cpp
+++ b/core/fxge/skia/cfx_dibbase_skia.cpp
@@ -33,41 +33,35 @@
 
 namespace {
 
-// Releases `CFX_DIBBase` "leaked" by `CreateSkiaImageFromDib()`.
+// Releases `CFX_DIBitmap` "leaked" by `CreateSkiaImageFromDib()`.
 void ReleaseRetainedHeldBySkImage(const void* /*pixels*/,
                                   SkImages::ReleaseContext context) {
-  RetainPtr<const CFX_DIBBase> retained;
-  retained.Unleak(reinterpret_cast<const CFX_DIBBase*>(context));
+  RetainPtr<const CFX_DIBitmap> realized_bitmap;
+  realized_bitmap.Unleak(reinterpret_cast<const CFX_DIBitmap*>(context));
 }
 
-// Creates an `SkImage` from a `CFX_DIBBase`, sharing the underlying pixels if
-// possible.
-//
-// Note that an `SkImage` must be immutable, so if sharing pixels, they must not
-// be modified during the lifetime of the `SkImage`.
+// Creates an `SkImage` from a `CFX_DIBBase`.
 sk_sp<SkImage> CreateSkiaImageFromDib(const CFX_DIBBase* source,
                                       SkColorType color_type,
                                       SkAlphaType alpha_type) {
   // Make sure the DIB is backed by a buffer.
-  RetainPtr<const CFX_DIBBase> retained;
-  if (source->GetBuffer().empty()) {
-    retained = source->Realize();
-    if (!retained) {
-      return nullptr;
-    }
-    DCHECK(!retained->GetBuffer().empty());
-  } else {
-    retained.Reset(source);
+  RetainPtr<const CFX_DIBitmap> realized_bitmap = source->RealizeIfNeeded();
+  if (!realized_bitmap) {
+    return nullptr;
   }
+  CHECK(!realized_bitmap->GetBuffer().empty());
 
-  // Convert unowned pointer to a retained pointer, then "leak" to `SkImage`.
-  source = retained.Leak();
-  SkImageInfo info = SkImageInfo::Make(source->GetWidth(), source->GetHeight(),
+  // Transfer ownership of `realized_bitmap` to `bitmap`, which will be freed by
+  // ReleaseRetainedHeldBySkImage().
+  const CFX_DIBitmap* bitmap = realized_bitmap.Leak();
+  SkImageInfo info = SkImageInfo::Make(bitmap->GetWidth(), bitmap->GetHeight(),
                                        color_type, alpha_type);
-  return SkImages::RasterFromPixmap(
-      SkPixmap(info, source->GetBuffer().data(), source->GetPitch()),
+  auto result = SkImages::RasterFromPixmap(
+      SkPixmap(info, bitmap->GetBuffer().data(), bitmap->GetPitch()),
       /*rasterReleaseProc=*/ReleaseRetainedHeldBySkImage,
-      /*releaseContext=*/const_cast<CFX_DIBBase*>(source));
+      /*releaseContext=*/const_cast<CFX_DIBitmap*>(bitmap));
+  CHECK(result);  // Otherwise, `bitmap` leaks.
+  return result;
 }
 
 // Releases allocated memory "leaked" by `CreateSkiaImageFromTransformedDib()`.
@@ -125,22 +119,6 @@
   DCHECK_GE(scanline.size(), min_row_bytes);
 }
 
-void ValidateBufferSize(pdfium::span<const uint8_t> buffer,
-                        const CFX_DIBBase& source) {
-#if DCHECK_IS_ON()
-  if (source.GetHeight() == 0) {
-    return;
-  }
-
-  FX_SAFE_SIZE_T buffer_size = source.GetHeight() - 1;
-  buffer_size *= source.GetPitch();
-  buffer_size += fxge::CalculatePitch8OrDie(source.GetBPP(), /*components=*/1,
-                                            source.GetWidth());
-
-  DCHECK_GE(buffer.size(), buffer_size.ValueOrDie());
-#endif  // DCHECK_IS_ON()
-}
-
 // Creates an `SkImage` from a `CFX_DIBBase`, transforming the source pixels
 // using `pixel_transform`.
 //
@@ -167,40 +145,21 @@
     return nullptr;
   }
 
-  // Transform source pixels to output pixels.
-  pdfium::span<const uint8_t> source_buffer = source.GetBuffer();
+  // Transform source pixels to output pixels. Iterate by individual scanline.
   Result* output_cursor = reinterpret_cast<Result*>(output.get());
-  if (source_buffer.empty()) {
-    // No buffer; iterate by individual scanline.
-    const size_t min_row_bytes =
-        fxge::CalculatePitch8OrDie(source.GetBPP(), /*components=*/1, width);
-    DCHECK_LE(min_row_bytes, source.GetPitch());
+  const size_t min_row_bytes =
+      fxge::CalculatePitch8OrDie(source.GetBPP(), /*components=*/1, width);
+  DCHECK_LE(min_row_bytes, source.GetPitch());
 
-    int line = 0;
-    for (int row = 0; row < height; ++row) {
-      pdfium::span<const uint8_t> scanline = source.GetScanline(line++);
-      ValidateScanlineSize(scanline, min_row_bytes);
+  int line = 0;
+  for (int row = 0; row < height; ++row) {
+    pdfium::span<const uint8_t> scanline = source.GetScanline(line++);
+    ValidateScanlineSize(scanline, min_row_bytes);
 
-      for (int column = 0; column < width; ++column) {
-        *output_cursor++ =
-            Traits::Invoke(std::forward<PixelTransform>(pixel_transform),
-                           scanline.data(), column);
-      }
-    }
-  } else {
-    // Iterate over the entire buffer.
-    ValidateBufferSize(source_buffer, source);
-    const size_t row_bytes = source.GetPitch();
-
-    const uint8_t* next_scanline = source_buffer.data();
-    for (int row = 0; row < height; ++row) {
-      const uint8_t* scanline = next_scanline;
-      next_scanline += row_bytes;
-
-      for (int column = 0; column < width; ++column) {
-        *output_cursor++ = Traits::Invoke(
-            std::forward<PixelTransform>(pixel_transform), scanline, column);
-      }
+    for (int column = 0; column < width; ++column) {
+      *output_cursor++ =
+          Traits::Invoke(std::forward<PixelTransform>(pixel_transform),
+                         scanline.data(), column);
     }
   }
 
diff --git a/core/fxge/win32/cgdi_device_driver.cpp b/core/fxge/win32/cgdi_device_driver.cpp
index e4c2b15..e6e2c21 100644
--- a/core/fxge/win32/cgdi_device_driver.cpp
+++ b/core/fxge/win32/cgdi_device_driver.cpp
@@ -394,7 +394,7 @@
                                      int left,
                                      int top) {
   if (m_DeviceType == DeviceType::kPrinter) {
-    RetainPtr<const CFX_DIBBase> flipped_source =
+    RetainPtr<const CFX_DIBitmap> flipped_source =
         source->FlipImage(/*bXFlip=*/false, /*bYFlip=*/true);
     if (!flipped_source) {
       return false;
@@ -414,7 +414,7 @@
     return true;
   }
 
-  RetainPtr<const CFX_DIBBase> realized_source = source->RealizeIfNeeded();
+  RetainPtr<const CFX_DIBitmap> realized_source = source->RealizeIfNeeded();
   if (!realized_source) {
     return false;
   }
@@ -445,7 +445,7 @@
     SetStretchBltMode(m_hDC, COLORONCOLOR);
   }
 
-  RetainPtr<const CFX_DIBBase> realized_source;
+  RetainPtr<const CFX_DIBitmap> realized_source;
   if (m_DeviceType == DeviceType::kPrinter &&
       ((int64_t)source->GetWidth() * source->GetHeight() >
        (int64_t)abs(dest_width) * abs(dest_height))) {
@@ -477,7 +477,7 @@
     return false;
   }
 
-  RetainPtr<const CFX_DIBBase> realized_source = source->RealizeIfNeeded();
+  RetainPtr<const CFX_DIBitmap> realized_source = source->RealizeIfNeeded();
   if (!realized_source) {
     return false;
   }
diff --git a/core/fxge/win32/cgdi_plus_ext.cpp b/core/fxge/win32/cgdi_plus_ext.cpp
index f6a9181..0cd0a37 100644
--- a/core/fxge/win32/cgdi_plus_ext.cpp
+++ b/core/fxge/win32/cgdi_plus_ext.cpp
@@ -223,7 +223,7 @@
     return;
   }
 
-  RetainPtr<const CFX_DIBBase> realized_source = source->RealizeIfNeeded();
+  RetainPtr<const CFX_DIBitmap> realized_source = source->RealizeIfNeeded();
   if (!realized_source) {
     return;
   }
diff --git a/testing/resources/pixel/bug_1478366.in b/testing/resources/pixel/bug_1478366.in
new file mode 100644
index 0000000..5749b52
--- /dev/null
+++ b/testing/resources/pixel/bug_1478366.in
@@ -0,0 +1,56 @@
+{{header}}
+{{object 1 0}} <<
+  /Type /Catalog
+  /Pages 2 0 R
+>>
+endobj
+{{object 2 0}} <<
+  /Type /Pages
+  /Count 1
+  /Kids [3 0 R]
+>>
+endobj
+{{object 3 0}} <<
+  /Type /Page
+  /Parent 2 0 R
+  /Contents [4 0 R]
+  /MediaBox [0 0 200 200]
+  /Resources <<
+    /XObject <<
+      /X1 5 0 R
+    >>
+  >>
+>>
+endobj
+{{object 4 0}} <<
+  {{streamlen}}
+>>
+stream
+q
+200 0 0 200 0 0 cm
+/X1 Do
+Q
+endstream
+endobj
+{{object 5 0}} <<
+  /Type /XObject
+  /Subtype /Image
+  % The image needs to have a bitmap size that's at least `kHugeImageSize`.
+  /Width 4000
+  /Height 4000
+  /BitsPerComponent 1
+  /ColorSpace /DeviceGray
+  /Filter [/ASCIIHexDecode /JBIG2Decode]
+  /Mask [255 255]
+  {{streamlen}}
+>>
+stream
+000000003000010000001300000dea00000353000017110000171151000000000001260001000000
+3500000dea000003530000000000000000020003fffdff02fefefeff7f86530fb6c922cfff7fff7f
+ff7fff7fff7fff7fff7fff7fffac
+endstream
+endobj
+{{xref}}
+{{trailer}}
+{{startxref}}
+%%EOF
diff --git a/testing/resources/pixel/bug_1478366_expected.pdf.0.png b/testing/resources/pixel/bug_1478366_expected.pdf.0.png
new file mode 100644
index 0000000..23e6296
--- /dev/null
+++ b/testing/resources/pixel/bug_1478366_expected.pdf.0.png
Binary files differ
diff --git a/testing/resources/pixel/bug_1478366_expected_skia.pdf.0.png b/testing/resources/pixel/bug_1478366_expected_skia.pdf.0.png
new file mode 100644
index 0000000..baf8b4b
--- /dev/null
+++ b/testing/resources/pixel/bug_1478366_expected_skia.pdf.0.png
Binary files differ