diff --git a/SDWebImage/SDWebImageDownloader.m b/SDWebImage/SDWebImageDownloader.m
index 9a984ab9..24e5e0d6 100644
--- a/SDWebImage/SDWebImageDownloader.m
+++ b/SDWebImage/SDWebImageDownloader.m
@@ -8,7 +8,6 @@
 
 #import "SDWebImageDownloader.h"
 #import "SDWebImageDownloaderOperation.h"
-#import <ImageIO/ImageIO.h>
 
 @implementation SDWebImageDownloadToken
 @end
diff --git a/SDWebImage/SDWebImageDownloaderOperation.m b/SDWebImage/SDWebImageDownloaderOperation.m
index 89d75ab9..c35ea1a8 100644
--- a/SDWebImage/SDWebImageDownloaderOperation.m
+++ b/SDWebImage/SDWebImageDownloaderOperation.m
@@ -48,10 +48,11 @@ typedef NSMutableDictionary<NSString *, id> SDCallbacksDictionary;
 @end
 
 @implementation SDWebImageDownloaderOperation {
-    size_t width, height;
+    size_t _width, _height;
 #if SD_UIKIT || SD_WATCH
-    UIImageOrientation orientation;
+    UIImageOrientation _orientation;
 #endif
+    CGImageSourceRef _imageSource;
 }
 
 @synthesize executing = _executing;
@@ -80,6 +81,10 @@ typedef NSMutableDictionary<NSString *, id> SDCallbacksDictionary;
 
 - (void)dealloc {
     SDDispatchQueueRelease(_barrierQueue);
+    if (_imageSource) {
+        CFRelease(_imageSource);
+        _imageSource = NULL;
+    }
 }
 
 - (nullable id)addHandlersForProgress:(nullable SDWebImageDownloaderProgressBlock)progressBlock
@@ -317,48 +322,55 @@ didReceiveResponse:(NSURLResponse *)response
     if ((self.options & SDWebImageDownloaderProgressiveDownload) && self.expectedSize > 0) {
         // The following code is from http://www.cocoaintheshell.com/2011/05/progressive-images-download-imageio/
         // Thanks to the author @Nyx0uf
-
+        
+        // Get the image data
+        NSData *imageData = [self.imageData copy];
         // Get the total bytes downloaded
-        const NSInteger totalSize = self.imageData.length;
-
+        const NSInteger totalSize = imageData.length;
+        // Get the finish status
+        BOOL finished = (self.expectedSize == totalSize);
+        
+        if (!_imageSource) {
+            _imageSource = CGImageSourceCreateIncremental(NULL);
+        }
         // Update the data source, we must pass ALL the data, not just the new bytes
-        CGImageSourceRef imageSource = CGImageSourceCreateWithData((__bridge CFDataRef)self.imageData, NULL);
-
-        if (width + height == 0) {
-            CFDictionaryRef properties = CGImageSourceCopyPropertiesAtIndex(imageSource, 0, NULL);
+        CGImageSourceUpdateData(_imageSource, (__bridge CFDataRef)imageData, finished);
+        
+        if (_width + _height == 0) {
+            CFDictionaryRef properties = CGImageSourceCopyPropertiesAtIndex(_imageSource, 0, NULL);
             if (properties) {
                 NSInteger orientationValue = -1;
                 CFTypeRef val = CFDictionaryGetValue(properties, kCGImagePropertyPixelHeight);
-                if (val) CFNumberGetValue(val, kCFNumberLongType, &height);
+                if (val) CFNumberGetValue(val, kCFNumberLongType, &_height);
                 val = CFDictionaryGetValue(properties, kCGImagePropertyPixelWidth);
-                if (val) CFNumberGetValue(val, kCFNumberLongType, &width);
+                if (val) CFNumberGetValue(val, kCFNumberLongType, &_width);
                 val = CFDictionaryGetValue(properties, kCGImagePropertyOrientation);
                 if (val) CFNumberGetValue(val, kCFNumberNSIntegerType, &orientationValue);
                 CFRelease(properties);
-
+                
                 // When we draw to Core Graphics, we lose orientation information,
                 // which means the image below born of initWithCGIImage will be
                 // oriented incorrectly sometimes. (Unlike the image born of initWithData
                 // in didCompleteWithError.) So save it here and pass it on later.
 #if SD_UIKIT || SD_WATCH
-                orientation = [[self class] orientationFromPropertyValue:(orientationValue == -1 ? 1 : orientationValue)];
+                _orientation = [[self class] orientationFromPropertyValue:(orientationValue == -1 ? 1 : orientationValue)];
 #endif
             }
         }
-
-        if (width + height > 0 && totalSize < self.expectedSize) {
+        
+        if (_width + _height > 0 && !finished) {
             // Create the image
-            CGImageRef partialImageRef = CGImageSourceCreateImageAtIndex(imageSource, 0, NULL);
-
+            CGImageRef partialImageRef = CGImageSourceCreateImageAtIndex(_imageSource, 0, NULL);
+            
 #if SD_UIKIT || SD_WATCH
             // Workaround for iOS anamorphic image
             if (partialImageRef) {
                 const size_t partialHeight = CGImageGetHeight(partialImageRef);
                 CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
-                CGContextRef bmContext = CGBitmapContextCreate(NULL, width, height, 8, width * 4, colorSpace, kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedFirst);
+                CGContextRef bmContext = CGBitmapContextCreate(NULL, _width, _height, 8, _width * 4, colorSpace, kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedFirst);
                 CGColorSpaceRelease(colorSpace);
                 if (bmContext) {
-                    CGContextDrawImage(bmContext, (CGRect){.origin.x = 0.0f, .origin.y = 0.0f, .size.width = width, .size.height = partialHeight}, partialImageRef);
+                    CGContextDrawImage(bmContext, (CGRect){.origin.x = 0.0f, .origin.y = 0.0f, .size.width = _width, .size.height = partialHeight}, partialImageRef);
                     CGImageRelease(partialImageRef);
                     partialImageRef = CGBitmapContextCreateImage(bmContext);
                     CGContextRelease(bmContext);
@@ -369,13 +381,14 @@ didReceiveResponse:(NSURLResponse *)response
                 }
             }
 #endif
-
+            
             if (partialImageRef) {
 #if SD_UIKIT || SD_WATCH
-                UIImage *image = [UIImage imageWithCGImage:partialImageRef scale:1 orientation:orientation];
+                UIImage *image = [UIImage imageWithCGImage:partialImageRef scale:1 orientation:_orientation];
 #elif SD_MAC
                 UIImage *image = [[UIImage alloc] initWithCGImage:partialImageRef size:NSZeroSize];
 #endif
+                CGImageRelease(partialImageRef);
                 NSString *key = [[SDWebImageManager sharedManager] cacheKeyForURL:self.request.URL];
                 UIImage *scaledImage = [self scaledImageForKey:key image:image];
                 if (self.shouldDecompressImages) {
@@ -384,14 +397,16 @@ didReceiveResponse:(NSURLResponse *)response
                 else {
                     image = scaledImage;
                 }
-                CGImageRelease(partialImageRef);
                 
                 [self callCompletionBlocksWithImage:image imageData:nil error:nil finished:NO];
             }
         }
-
-        if (imageSource) {
-            CFRelease(imageSource);
+        
+        if (finished) {
+            if (_imageSource) {
+                CFRelease(_imageSource);
+                _imageSource = NULL;
+            }
         }
     }