diff --git a/SDWebImageWebPCoder/Classes/SDImageWebPCoder.m b/SDWebImageWebPCoder/Classes/SDImageWebPCoder.m
index 5675170..9aec9ff 100644
--- a/SDWebImageWebPCoder/Classes/SDImageWebPCoder.m
+++ b/SDWebImageWebPCoder/Classes/SDImageWebPCoder.m
@@ -736,6 +736,9 @@ static CGSize SDCalculateThumbnailSize(CGSize fullSize, BOOL preserveAspectRatio
     }
     
     size_t bytesPerRow = CGImageGetBytesPerRow(imageRef);
+    size_t bitsPerComponent = CGImageGetBitsPerComponent(imageRef);
+    size_t bitsPerPixel = CGImageGetBitsPerPixel(imageRef);
+    size_t components = bitsPerPixel / bitsPerComponent;
     CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
     CGImageAlphaInfo alphaInfo = bitmapInfo & kCGBitmapAlphaInfoMask;
     CGBitmapInfo byteOrderInfo = bitmapInfo & kCGBitmapByteOrderMask;
@@ -763,10 +766,15 @@ static CGSize SDCalculateThumbnailSize(CGSize fullSize, BOOL preserveAspectRatio
     if (!dataRef) {
         return nil;
     }
+    // Check colorSpace is RGB/RGBA
+    CGColorSpaceRef colorSpace = CGImageGetColorSpace(imageRef);
+    BOOL isRGB = CGColorSpaceGetModel(colorSpace) == kCGColorSpaceModelRGB;
     
     uint8_t *rgba = NULL; // RGBA Buffer managed by CFData, don't call `free` on it, instead call `CFRelease` on `dataRef`
     // We could not assume that input CGImage's color mode is always RGB888/RGBA8888. Convert all other cases to target color mode using vImage
-    if (byteOrderNormal && ((alphaInfo == kCGImageAlphaNone) || (alphaInfo == kCGImageAlphaLast))) {
+    BOOL isRGB888 = isRGB && byteOrderNormal && alphaInfo == kCGImageAlphaNone && components == 3;
+    BOOL isRGBA8888 = isRGB && byteOrderNormal && alphaInfo == kCGImageAlphaLast && components == 4;
+    if (isRGB888 || isRGBA8888) {
         // If the input CGImage is already RGB888/RGBA8888
         rgba = (uint8_t *)CFDataGetBytePtr(dataRef);
     } else {
@@ -775,10 +783,11 @@ static CGSize SDCalculateThumbnailSize(CGSize fullSize, BOOL preserveAspectRatio
         vImage_Error error = kvImageNoError;
         
         vImage_CGImageFormat srcFormat = {
-            .bitsPerComponent = (uint32_t)CGImageGetBitsPerComponent(imageRef),
-            .bitsPerPixel = (uint32_t)CGImageGetBitsPerPixel(imageRef),
-            .colorSpace = CGImageGetColorSpace(imageRef),
-            .bitmapInfo = bitmapInfo
+            .bitsPerComponent = (uint32_t)bitsPerComponent,
+            .bitsPerPixel = (uint32_t)bitsPerPixel,
+            .colorSpace = colorSpace,
+            .bitmapInfo = bitmapInfo,
+            .renderingIntent = CGImageGetRenderingIntent(imageRef)
         };
         vImage_CGImageFormat destFormat = {
             .bitsPerComponent = 8,
@@ -793,14 +802,15 @@ static CGSize SDCalculateThumbnailSize(CGSize fullSize, BOOL preserveAspectRatio
             return nil;
         }
         
-        vImage_Buffer src = {
-            .data = (uint8_t *)CFDataGetBytePtr(dataRef),
-            .width = width,
-            .height = height,
-            .rowBytes = bytesPerRow
-        };
-        vImage_Buffer dest;
+        vImage_Buffer src;
+        error = vImageBuffer_InitWithCGImage(&src, &srcFormat, nil, imageRef, kvImageNoFlags);
+        if (error != kvImageNoError) {
+            vImageConverter_Release(convertor);
+            CFRelease(dataRef);
+            return nil;
+        }
         
+        vImage_Buffer dest;
         error = vImageBuffer_Init(&dest, height, width, destFormat.bitsPerPixel, kvImageNoFlags);
         if (error != kvImageNoError) {
             vImageConverter_Release(convertor);
diff --git a/Tests/Images/TestImageGrayscale.jpg b/Tests/Images/TestImageGrayscale.jpg
new file mode 100644
index 0000000..9f630ea
Binary files /dev/null and b/Tests/Images/TestImageGrayscale.jpg differ
diff --git a/Tests/SDWebImageWebPCoderTests.m b/Tests/SDWebImageWebPCoderTests.m
index e47b5a5..ef1de63 100644
--- a/Tests/SDWebImageWebPCoderTests.m
+++ b/Tests/SDWebImageWebPCoderTests.m
@@ -292,6 +292,35 @@ const int64_t kAsyncTestTimeout = 5;
     expect(config.method).to.equal(4);
 }
 
+
+- (void)testEncodingGrayscaleImage {
+    NSURL *grayscaleImageURL = [[NSBundle bundleForClass:[self class]] URLForResource:@"TestImageGrayscale" withExtension:@"jpg"];
+    NSData *grayscaleImageData = [NSData dataWithContentsOfURL:grayscaleImageURL];
+    UIImage *grayscaleImage = [[UIImage alloc] initWithData:grayscaleImageData];
+    expect(grayscaleImage).notTo.beNil();
+    
+    NSData *webpData = [SDImageWebPCoder.sharedCoder encodedDataWithImage:grayscaleImage format:SDImageFormatWebP options:nil];
+    expect(webpData).notTo.beNil();
+    
+    UIImage *decodedImage = [UIImage sd_imageWithData:webpData];
+    expect(decodedImage).notTo.beNil();
+    
+    // Sample to verify that encoded WebP image's color is correct.
+    // The wrong case before bugfix is that each column color will repeats 3 times.
+    CGPoint point1 = CGPointMake(271, 764);
+    CGPoint point2 = CGPointMake(round(point1.x + decodedImage.size.width / 3), point1.y);
+    UIColor *color1 = [decodedImage sd_colorAtPoint:point1];
+    UIColor *color2 = [decodedImage sd_colorAtPoint:point2];
+    CGFloat r1, r2;
+    CGFloat g1, g2;
+    CGFloat b1, b2;
+    [color1 getRed:&r1 green:&g1 blue:&b1 alpha:nil];
+    [color2 getRed:&r2 green:&g2 blue:&b2 alpha:nil];
+    expect(255 * r1).notTo.equal(255 * r2);
+    expect(255 * g1).notTo.equal(255 * g2);
+    expect(255 * b1).notTo.equal(255 * b2);
+}
+
 @end
 
 @implementation SDWebImageWebPCoderTests (Helpers)
diff --git a/Tests/SDWebImageWebPCoderTests.xcodeproj/project.pbxproj b/Tests/SDWebImageWebPCoderTests.xcodeproj/project.pbxproj
index 976c098..2b15956 100644
--- a/Tests/SDWebImageWebPCoderTests.xcodeproj/project.pbxproj
+++ b/Tests/SDWebImageWebPCoderTests.xcodeproj/project.pbxproj
@@ -9,6 +9,7 @@
 /* Begin PBXBuildFile section */
 		0EF5B6264833B7BC20894578 /* Pods_SDWebImageWebPCoderTests.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 46F21AD7D1692EBAC4D0FF33 /* Pods_SDWebImageWebPCoderTests.framework */; };
 		3219F3B2228B0453003822A6 /* TestImageBlendAnimated.webp in Resources */ = {isa = PBXBuildFile; fileRef = 3219F3B1228B0453003822A6 /* TestImageBlendAnimated.webp */; };
+		325E268E25C82BE1000B807B /* TestImageGrayscale.jpg in Resources */ = {isa = PBXBuildFile; fileRef = 325E268D25C82BE1000B807B /* TestImageGrayscale.jpg */; };
 		808C918E213FD131004B0F7C /* SDWebImageWebPCoderTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 808C918D213FD131004B0F7C /* SDWebImageWebPCoderTests.m */; };
 		808C919C213FD2B2004B0F7C /* TestImageStatic.webp in Resources */ = {isa = PBXBuildFile; fileRef = 808C919A213FD2B2004B0F7C /* TestImageStatic.webp */; };
 		808C919D213FD2B2004B0F7C /* TestImageAnimated.webp in Resources */ = {isa = PBXBuildFile; fileRef = 808C919B213FD2B2004B0F7C /* TestImageAnimated.webp */; };
@@ -17,6 +18,7 @@
 /* Begin PBXFileReference section */
 		28D8AA3D3015E075692FD3E3 /* Pods-SDWebImageWebPCoderTests.debug.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-SDWebImageWebPCoderTests.debug.xcconfig"; path = "../Pods/Target Support Files/Pods-SDWebImageWebPCoderTests/Pods-SDWebImageWebPCoderTests.debug.xcconfig"; sourceTree = "<group>"; };
 		3219F3B1228B0453003822A6 /* TestImageBlendAnimated.webp */ = {isa = PBXFileReference; lastKnownFileType = file; path = TestImageBlendAnimated.webp; sourceTree = "<group>"; };
+		325E268D25C82BE1000B807B /* TestImageGrayscale.jpg */ = {isa = PBXFileReference; lastKnownFileType = image.jpeg; path = TestImageGrayscale.jpg; sourceTree = "<group>"; };
 		46F21AD7D1692EBAC4D0FF33 /* Pods_SDWebImageWebPCoderTests.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = Pods_SDWebImageWebPCoderTests.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		808C918B213FD130004B0F7C /* SDWebImageWebPCoderTests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = SDWebImageWebPCoderTests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
 		808C918D213FD131004B0F7C /* SDWebImageWebPCoderTests.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = SDWebImageWebPCoderTests.m; sourceTree = "<group>"; };
@@ -78,6 +80,7 @@
 		808C9199213FD2B2004B0F7C /* Images */ = {
 			isa = PBXGroup;
 			children = (
+				325E268D25C82BE1000B807B /* TestImageGrayscale.jpg */,
 				808C919A213FD2B2004B0F7C /* TestImageStatic.webp */,
 				808C919B213FD2B2004B0F7C /* TestImageAnimated.webp */,
 				3219F3B1228B0453003822A6 /* TestImageBlendAnimated.webp */,
@@ -154,6 +157,7 @@
 				3219F3B2228B0453003822A6 /* TestImageBlendAnimated.webp in Resources */,
 				808C919D213FD2B2004B0F7C /* TestImageAnimated.webp in Resources */,
 				808C919C213FD2B2004B0F7C /* TestImageStatic.webp in Resources */,
+				325E268E25C82BE1000B807B /* TestImageGrayscale.jpg in Resources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};