diff --git a/DirectXTex/DirectXTexMisc.cpp b/DirectXTex/DirectXTexMisc.cpp
index 7b787cd7..204636d4 100644
--- a/DirectXTex/DirectXTexMisc.cpp
+++ b/DirectXTex/DirectXTexMisc.cpp
@@ -260,8 +260,64 @@ _Use_decl_annotations_ HRESULT DirectX::CopyRectangle(const Image& srcImage,
     if (!srcImage.pixels || !dstImage.pixels)
         return E_POINTER;
 
-    if (IsCompressed(srcImage.format) || IsCompressed(dstImage.format) || IsPlanar(srcImage.format) || IsPlanar(dstImage.format)
-        || IsPalettized(srcImage.format) || IsPalettized(dstImage.format))
+    if (IsCompressed(srcImage.format) || IsCompressed(dstImage.format))
+    {
+        if (srcImage.format != dstImage.format)
+            return HRESULT_E_NOT_SUPPORTED;
+
+        const size_t bytesPerBlock = BytesPerBlock(srcImage.format);
+        if (!bytesPerBlock)
+            return HRESULT_E_NOT_SUPPORTED;
+
+        if (!srcRect.w || !srcRect.h || srcRect.x >= srcImage.width || srcRect.y >= srcImage.height
+            || srcRect.w > srcImage.width - srcRect.x || srcRect.h > srcImage.height - srcRect.y || xOffset >= dstImage.width
+            || yOffset >= dstImage.height || srcRect.w > dstImage.width - xOffset || srcRect.h > dstImage.height - yOffset)
+            return E_INVALIDARG;
+
+        // Copy whole 4x4 blocks covering srcRect, including pixels outside it.
+        // Round the destination origin down to a block boundary.
+        const size_t srcX = srcRect.x / 4;
+        const size_t srcY = srcRect.y / 4;
+        const size_t dstX = xOffset / 4;
+        const size_t dstY = yOffset / 4;
+
+        const size_t blockWidth  = (srcRect.x + srcRect.w - 1) / 4 + 1 - srcX;
+        const size_t blockHeight = (srcRect.y + srcRect.h - 1) / 4 + 1 - srcY;
+        const size_t dstWidth    = (dstImage.width - 1) / 4 + 1;
+        const size_t dstHeight   = (dstImage.height - 1) / 4 + 1;
+        if (blockWidth > dstWidth - dstX || blockHeight > dstHeight - dstY)
+            return E_INVALIDARG;
+
+        const auto validStorage = [bytesPerBlock](const Image& image, size_t x, size_t y, size_t width, size_t height) noexcept
+        {
+            const size_t imageBlocks = (image.width - 1) / 4 + 1;
+            if (!image.rowPitch || imageBlocks > image.rowPitch / bytesPerBlock)
+                return false;
+
+            const size_t rowEnd = (x + width) * bytesPerBlock;
+            return rowEnd <= image.slicePitch && y + height - 1 <= (image.slicePitch - rowEnd) / image.rowPitch;
+        };
+
+        if (!validStorage(srcImage, srcX, srcY, blockWidth, blockHeight) || !validStorage(dstImage, dstX, dstY, blockWidth, blockHeight))
+            return E_FAIL;
+
+        const size_t   copyBytes = blockWidth * bytesPerBlock;
+        const uint8_t* pSrc      = srcImage.pixels + srcY * srcImage.rowPitch + srcX * bytesPerBlock;
+        uint8_t*       pDest     = dstImage.pixels + dstY * dstImage.rowPitch + dstX * bytesPerBlock;
+        for (size_t row = 0; row < blockHeight; ++row)
+        {
+            memcpy(pDest, pSrc, copyBytes);
+            if (row + 1 < blockHeight)
+            {
+                pSrc += srcImage.rowPitch;
+                pDest += dstImage.rowPitch;
+            }
+        }
+
+        return S_OK;
+    }
+
+    if (IsPlanar(srcImage.format) || IsPlanar(dstImage.format) || IsPalettized(srcImage.format) || IsPalettized(dstImage.format))
         return HRESULT_E_NOT_SUPPORTED;
 
     // Validate rectangle/offset