How to extract Scalado-Thumbnail ?

[dschordsch]

Hello,

I'm using ExifTool 9.35 (exiftool.exe) and ExifToolGUI 5.15 (exiftoolgui.exe) on Windows.
With ExifToolGUI  I found special thumbnail data in an image file of a HTC Desire:

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---- IFD1 ----
ThumbnailOffset 448
ThumbnailLength 25405

---- Scalado ----
DataLength 264
PreviewImageView 1296
PreviewImageHeight 776
PreviewQuality 85


With ExifTool I could extract IFD1 thumbnail with

exiftool -if $ThumbnailImage -b -ThumbnailImage [name.jpg] > tn.jpg

This command extracted thumbnail with size 800x480 (IFD1-TN).

Then I tried to extract the Scalado thumbnail with

exiftool if $PreviewImage -b -PreviewImage [name.jpg] > tn.jpg
and
exiftool if $PhotoshopThumbnail -b -PhotoshopThumbnail [name.jpg] > tn.jpg
and
exiftool if $ScaladoImage -b -ScaladoImage [name.jpg] > tn.jpg
and
exiftool if $ScaladoThumbnail -b -ScaladoThumbnail [name.jpg] > tn.jpg   

with no result.

I tried to get more info with

exiftool -htmlDump0 [name.jpg] > dump.html
   
This dump showed three APP4 SCALADO segments directly behind IFD1 thumbnail data
      
1. APP4 SCALADO segment with 65537 bytes
2. APP4 SCALADO segment with 65537 bytes
3. APP4 SCALADO segment with 14562 bytes

I have a link to the example image of a HTC Desire:

https://www.dropbox.com/sh/0d7m2l8n6mcmib4/_rjlZ3tnh7?lst


My question: Is there a way to extract such SCALADO thumbnails with exiftool.exe ?

[Phil Harvey]

There is no trick or any guesswork necessary in cases like this, although for some reason this is a common source of confusion.

To look for all available images, this is a useful command:

exiftool -a FILE | grep Binary

If you don't have the "grep" utility, then just look for tags which report values like "(Binary data ### bytes, use -b option to extract)".  Any images extractable by ExifTool will show up in this list:

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> exiftool -a ~/Desktop/IMAG0122.jpg | grep Bin
Thumbnail Image                 : (Binary data 25405 bytes, use -b option to extract)

So for the sample you provided, only a ThumbnailImage may be extracted.  (Thanks for the sample, btw.)

Looking at the APP4 information, I can't see an embedded JPEG image that ExifTool could extract.  There is a lot of data there, presumably containing the preview in some other form.  In general, ExifTool only extracts embedded images which are stand-alone file formats, and not ones that are image data only, which this may be.  But I'll study the sample a bit more to see if there is anything else that can be extracted.

- Phil

[Phil Harvey]

You can extract any number of embedded images with a single command, like this:

exiftool -W %d%f_%t.%s -b -thumbnailimage -previewimage ... DIR

Currently you need to list all of the tags separately, but I'm thinking about adding a new group to allow these to be specified all at once.

- Phil