ExifTool Forum

[Originally posted by gmikol on 2008-11-01 01:05:45-07]

Hi--

I've have a bunch of Canon CRW files from a PowerShot S70 with 640x480 JPGFromRaw images. I've generated new, larger JPG's that I want to embed into the CRW files. I'm having trouble with it, though, and the Canon viewer, ZoomBrowser (ZB), isn't recognizing the new file fully.

The commands I'm using (in Windows) are:


Bigger problem is that my results are variable depending on the order of the steps:

1) If I just write the ThumbnailImage, everything works fine

2) If I just write the JPGFromRaw, ZB recognizes the file and can convert the RAW, but it does not use the JPGFromRaw image for viewing

3) Same results as #2 if I write the JPGFromRaw and then the ThumbnailImage

4) If I write the ThumbnailImage and then the JPGFromRaw, then the file is corrupted, ZB doesn't recognize it, and it can't convert the RAW.

I tried using the -F option in case it was a MakerNotes offset, but the results are the same.

I really don't know how to troubleshoot any further myself, so I'm hoping for some collective help.

I'm using the latest release (7.51)

Thanks--

Greg

[Originally posted by bogdan on 2008-11-01 06:35:43-07]

Hi Greg,

I don't have any CRW file by hand, but if I recall correctly, then CRW files don't contain embedded thumbnails -thumbnails are saved into separate THW files.

Bogdan

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[Originally posted by exiftool on 2008-11-01 14:42:15-07]

Thanks for reporting this problem.

I have the Canon utilities here so I will test this out.
It is understandable that ZoomBrowser has problems
if the Jpgfromraw is the wrong size, but there must
be some quirk about the ordering of data within the
file that it causing problems when writing the
thumbnailimage first.

I will get to this as soon as I can, but I am away this
weekend so give me a few days.

(Bogdan: Some powershot models do store a thumbnail
inside the CRW -- EOS models use a separate THM file.)

- Phil

[Originally posted by gmikol on 2008-11-01 15:41:19-07]

Actually, my PowerShot (S70) does both. It writes a separate THM and embeds the ThumbnailImage in the CRW. Don't know why it does that, but I figured all this out while I was trying to figure out what utilities use the embedded, and which use the THM.

You say "...if the JPGFromRaw is the wrong size...". I got the impression from the documentation that ExifTool was capable of resizing the ThumbnailImage and JPGFromRaw fields. I've stepped back and tried to use a 640x480 image instead of a higher-res one, and still got the same problems. This way, I shouldn't have to worry about the RawJpgInfo tags.

Let me know if you need sample files...

--Greg

[Originally posted by exiftool on 2008-11-02 17:57:29-08]

Hi Greg,

Yes, exiftool can resize the fields, but my concern is that the zoombrowser
may be expecting an image of certain dimensions (if the software is
very inflexible).  This is possible, but I don't know how likely it is.

An S70 sample would be useful.  (You can email it to me at philharvey66 at gmail.com).
I have tested this with S30, S40, S50 and G3 CRW images (I don't have an S70 CRW
handy) using Canon ImageBrowser 3.0 (the Mac equivalent of zoombrowser),
but it doesn't have a problem with any of the images.  I have tried deleting
both thumbnailimage and jpgfromraw then adding them back again in
both orders and it doesn't complain about anything.  So it is either
something different with S70 images, something different about zoombrowser
or something different that you are doing.  Do you have the same problem
if you extract the thumbnailimage and jpgfromraw from an original CRW
image then put the same images back into the CRW?  ie)


If this doesn't cause problems for you, please send me a set of commands
that does.

Also, what version of zoombrowser are you using?  I will see
if I can load the same version onto the PC to duplicate the
exact steps that are causing you problems.

- Phil

[Originally posted by gmikol on 2008-11-03 08:51:42-08]

Phil--

First off, I'm using ZoomBrowser 6.11 under WinXP SP3. ActivePerl 5.10.0 Build 1003, ExifTool 7.51

Thanks for your help...I don't have any trouble with the set of commands you provided. The problem comes from trying to write a different file into the JPGFromRaw tag.

Seems to work fine by itself.

Breaks the display of the preview image in ZB. It looks like it takes the thumb and up-rezzes it to the correct pixel size instead. But it will still process the RAW.

Works fine as well, but not very useful.

Breaks the file to the point that the Canon software won't convert the RAW. Same result if I clear the JPGFromRaw tag before writing the JFR image back. But it works fine if, as the 4th command, I write the original thumbnail back.

I've sent you a ZIP file with all the necessary pieces you can use to test this for yourself. The new_jfr.jpg file is 640x480 for now, the same size as the original jfr.jpg. Ultimately, I'd like to embed a bigger JFR, but I'll worry about that when (if) this gets working.

Also, is there anyone out there who is successfully writing new JPGFromRaw images into your CRW files and they still work in ZoomBrowser?

--Greg

[Originally posted by exiftool on 2008-11-03 11:22:32-08]

Hi Greg,

Thanks for the samples.  I will test this in the PC when I get home
tonight, but I have an idea that you can test:  Try deleting the
JFIF information from your new thumb and jfr images (with
"-jfif:all=") before writing them to the CRW.  Just looking at the
files, this difference jumps out at me and I'm wondering if it
could cause problems somehow for the Canon software.

- Phil

[Originally posted by gmikol on 2008-11-03 16:10:41-08]



I tried this, and got the same results. The files I was originally playing around with last week when I found these problems didn't have any JFIF tags. But those files had a different  YCbCr Subsampling parameter than the Canon originals. So I used an IrfanView plugin that allows you to specify this parameter in the JPG compression, but it didn't make any difference.

--Greg

[Originally posted by exiftool on 2008-11-04 00:18:39-08]

yes, i thought about YCbCr too, but noticed
it was the same.

I fired up the PC tonight, hoping my zoombrowser
would have the same problem, but it didn't. I was
using zoombrowser EX 4.1.1, which is from
2003.  After following the same steps as you
it still appeared to display the jpgfromraw,
but it wouldn't convert the raw image
(even for the original) -- it must be too old
for the S70.  So my next step is to update
my zoombrowser, but this will have to wait
until tomorrow. - Phil

[Originally posted by exiftool on 2008-11-04 23:37:29-08]

Well, zoombrowser 6.1.1 wouldn't install for me (it gave an extract error),
but the good news is imagebrowser 6.1.1 installed OK and gave me the
same symptoms that you were observing.

So I have been able to reproduce the problem and it is solved.  This was
partly a bug in exiftool and partly a difference with the new utilities.
The problem was with data alignment, and the problem only manifested
itself for images with an odd number of bytes.

Thanks for the bug report, for the samples to allow me to reproduce this,
and for your patience.

I have just released exiftool 7.52 which should solve this for you.

- Phil

[Originally posted by gmikol on 2008-11-05 04:34:31-08]

Phil--

Thank you for your response and attention to this issue. I just downloaded the new version, installed it and tested it out on the same set of images I sent you.

The issue with the CRW image file being completely corrupted is resolved. It seems that no matter what order I write tags in, it's still convertable by Raw Image Task. So that's good.

Perhaps the other issue can't be resolved, but when I write the new_jfr.jpg to JPGFromRaw, it still doesn't show up in ZB correctly. It's still a highly pixelated version of the thumbnail, instead of the obvious new JPGFromRaw image. Is this working fine on your Mac version (ImageBrowser)? Did you confirm this part of the functionality?

--Greg

[Originally posted by exiftool on 2008-11-05 11:33:53-08]

Hi Greg,

I did confirm that this worked for the Mac version (I even
generated a jpgFromRaw that was a different image from
the thumbnail for some of my tests to make it obvious
which was displayed).

I'll have another go at installing zoombrowser to see
if I can figure this one out.  Did you confirm that the
jpgFromRaw is displayed if you put the original one
back into the file?

- Phil

[Originally posted by gmikol on 2008-11-06 06:35:57-08]

Yeah...I can take it all apart and put it back together the way I found it. And it works fine, which is a definite improvement, but I can't embed a *new* JPGFromRaw into the CRW and have it display properly in ZoomBrowser.

--Greg

[Originally posted by exiftool on 2008-11-06 11:45:58-08]

OK, thanks Greg.  Any testing you can do will help.  We should
be able to figure this one out.  I've re-downloaded the ZB 6.1.1
update but it still won't install on my PC running XP service pack2.
My next step is to see if I can find another PC to install it on.

I repeated the tests with ImageBrowser, and it worked flawlessly,
displaying whatever JpgFromRaw I write without a hiccup (although
I admit that I have only tried 640x480 images so far).
So the is a ZB-specific quirk.

- Phil

[Originally posted by gmikol on 2008-11-06 19:27:48-08]

Sure thing, Phil...I'm happy to do any testing. Just let me know what you need...

--Greg

[Originally posted by exiftool on 2008-11-07 23:16:15-08]

Well, after a couple more wasted hours trying to install the
zoombrowser update, I finally got it to work, so I have
been able to try a few things myself.  The symptoms I
observe are different than you:  I can't get ZB to display
either a thumbnail or a jpgfromraw other than the original.
I wonder if we are running a slightly different version of ZB.
I'm running 6.1.1.21.  Also, I am running Service pack 2,
but I don't see how that could affect things.

But after a number of tests, I have narrowed down the
possible causes for not displaying the embedded images:

- it isn't the YCbCrSubSampling (but you knew that already)

- it isn't any of the metadata (ie. JFIF)

- it isn't the image dimensions

- it isn't the image file size (I tried adding junk to the end of
both the original and your new images to make them the same length,
but the Canon ones still worked while the new ones didn't)

- it isn't the image encoding process (all baseline DCT, Huffman)

I could only think of one thing that was left:

- it could be that the quantization tables are different

So I did some specific tests and confirmed that this is the reason.
If I copy the quantization tables (DQT segment) and huffman
tables (DHT segment) from the Canon image and use them in the
new image, then ZB will display this embedded image.  Very odd.
(Copying either the DQT or the DHT alone doesn't work, they both
must be copied.) The only reason I could imagine why this would
happen is if Canon intentionally checks for Canon-specific tables
and disables display of other embedded images.

Very crazy indeed, but those are the facts.

Unfortunately I know if no utilities that will allow you
to use a specific set of quantization tables.  I had the
bright idea of using ZB to rewrite the JPEG before embedding
it, but sadly that didn't work.

So it looks like there is no simple solution to the problem,
short of finding or writing a utility to use a specific set
of quantization tables in the JPEG transform.

- Phil

[Originally posted by gmikol on 2008-11-08 02:49:21-08]

Well, thanks for all your help, Phil.

For everyone who reads this in the future. JpgFromRaw images embedded with ExifTool v7.52 will display correctly in ZoomBrowser 5.0 and 5.5 (and presumably 5.7, which I didn't test). They do not display correctly in 6.01 and 6.11.

It's a shame Canon changed the way they're parsing the CRW files, if I thought I could get Canon to do anything about it, I would beg and whine and cry piteously until they did. But I can't...so I won't.

Thanks again--

--Greg

[Originally posted by bogdan on 2008-11-08 14:53:27-08]

Hi,

I didn't dig deeper into this, but... As far I recall, for ZB v6.xx, ZoomBrowser started to use .NET library. Maybe this is somehow related with issue you have. It's just a though.

Greetings,

Bogdan