App Engine和云端存储生成缩略图图像的文件大小比原始图像大 [英] App Engine and Cloud Storage I generate thumbnail image has larger file size than original image

问题描述

我的功能适用于我，但缩略图文件大小大于原始文件大小。 原始文件：30Kb b
$ b

缩略图文件：50Kb

My Function

  public static void thumbnailImage（String filename，int width ，int height）throws IOException {
 GcsService gcsService = GcsServiceFactory.createGcsService（new RetryParams.Builder（）
 .initialRetryDelayMillis（10）
 .retryMaxAttempts（10）
 .totalRetryPeriodMillis（15000 ）
 .build（））; 
 AppIdentityService appIdentity = AppIdentityServiceFactory.getAppIdentityService（）; 
 ImagesService imagesService = ImagesServiceFactory.getImagesService（）; 
 //从Cloud Storage对象制作图像并对其进行转换。 
 BlobstoreService blobstoreService = BlobstoreServiceFactory.getBlobstoreService（）; 
 BlobKey blobKey = blobstoreService.createGsBlobKey（/ gs /+ appIdentity.getDefaultGcsBucketName（）+/+ filename）; 
 
 Image thumb = null; 
尝试{
 Image blobImage = ImagesServiceFactory.makeImageFromBlob（blobKey）; 
 Transform resize = ImagesServiceFactory.makeResize（width，height）; 
 thumb = imagesService.applyTransform（resize，blobImage）; 
 
} catch（Exception e）{
 e.printStackTrace（）; 
} 
字符串扩展名= Files.getFileExtension（filename）; 
 filename = stripExtension（filename）; 
 filename = String.format（％1 $ s_％2 $ s。％3 $ s，文件名，缩略图，扩展名）; 
 
 if（thumb！= null）
 //将转换后的图像写回云存储对象。 
 gcsService.createOrReplace（
 new GcsFilename（appIdentity.getDefaultGcsBucketName（），filename），
 new GcsFileOptions.Builder（）。mimeType（image / jpeg）。acl（public-read ）.build（），
 ByteBuffer.wrap（thumb.getImageData（）））; 
} 
  

原始文件仅为 30KB ，但缩略图是 50KB 。它们具有相同的V分辨率和H分辨率 96dpi 和位深度 24 。还有什么我错过了吗？有很多类似的问题，我不确定我的问题是否重复。

编辑：

这是Google云端的连结

https://storage.googleapis.com/exalted-etching-131403.appspot.com/pro/abc/door-baby-bouncer.jpg

缩略图：

https://storage.googleapis.com/exalted-etching-131403.appspot.com/pro/abc /door-bouncer_thumbnail.jpg

解决方案

感谢tx802和jterrace

我现在找到了解决方案。我添加OutputSettings来转换函数以将Encoding更改为JPEG

  thumb = imagesService.applyTransform（resize，blobImage，new OutputSettings（OutputEncoding。 JPEG））; 
  

现在我的缩略图只有5Kb。

My function work for me but the thumbnail image file size is larger than original file size.

Original File: 30Kb

Thumbnail File: 50Kb

My Function

public static void thumbnailImage(String filename, int width, int height) throws IOException{
    GcsService gcsService = GcsServiceFactory.createGcsService(new RetryParams.Builder()
              .initialRetryDelayMillis(10)
              .retryMaxAttempts(10)
              .totalRetryPeriodMillis(15000)
              .build());
    AppIdentityService appIdentity = AppIdentityServiceFactory.getAppIdentityService();
    ImagesService imagesService = ImagesServiceFactory.getImagesService();
    // Make an image from a Cloud Storage object, and transform it.
    BlobstoreService blobstoreService = BlobstoreServiceFactory.getBlobstoreService();
    BlobKey blobKey = blobstoreService.createGsBlobKey("/gs/" + appIdentity.getDefaultGcsBucketName() +"/"+ filename);

    Image thumb = null;
    try{
        Image blobImage = ImagesServiceFactory.makeImageFromBlob(blobKey);          
        Transform resize = ImagesServiceFactory.makeResize(width, height);
        thumb = imagesService.applyTransform(resize, blobImage);

    }catch(Exception e){
        e.printStackTrace();
    }
    String extension = Files.getFileExtension(filename);
    filename = stripExtension(filename);
    filename = String.format("%1$s_%2$s.%3$s", filename, thumbnail, extension);

    if(thumb!=null)
    // Write the transformed image back to a Cloud Storage object.
    gcsService.createOrReplace(
        new GcsFilename(appIdentity.getDefaultGcsBucketName(), filename),
        new GcsFileOptions.Builder().mimeType("image/jpeg").acl("public-read").build(),
        ByteBuffer.wrap(thumb.getImageData()));
}

The original file is only 30KB, but the thumbnail is 50KB. They have the same V-Resolution and H-Resolution 96dpi and Bit Depth 24. Are there something else I have missed? There are a lot of similar Questions, I'm not sure if my question is duplicated.

EDIT:

this is link on google cloud

https://storage.googleapis.com/exalted-etching-131403.appspot.com/pro/abc/door-baby-bouncer.jpg

thumbnail:

https://storage.googleapis.com/exalted-etching-131403.appspot.com/pro/abc/door-baby-bouncer_thumbnail.jpg

解决方案

Thank tx802 and jterrace

I found the solution now. I add OutputSettings to transform function to change Encoding to JPEG

thumb = imagesService.applyTransform(resize, blobImage, new OutputSettings(OutputEncoding.JPEG));

Right now my thumbnail image is only 5Kb.

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