[Digikam-users] Re: can't view scanned tiff images

[Jim Dory]

On Sun, Dec 5, 2010 at 11:55 AM, Jim Dory <james at dorydesign.com> wrote:
> On Sun, Dec 5, 2010 at 11:40 AM, Jim Dory <james at dorydesign.com> wrote:
>> On Sun, Dec 5, 2010 at 10:02 AM, Marcel Wiesweg <marcel.wiesweg at gmx.de> wrote:
>>>
>>>
>>>> I scan images using a proprietary Vuescan (www.hamrick.com) which
>>>> supports Linux and my Nikon LS9000 film scanner. I may have a setting
>>>> wrong in Vuescan or Digikam that after I scan an image (they can be
>>>> quite large - ~50MB or more) Digikam complains that it cannot open the
>>>> tif file. I have the output set in Vuescan as a 24 bit RGB file type,
>>>> with Auto compression. Choices on the file type are 24 Bit and higher
>>>> RGB, or lower B & W.
>>>
>>> The TIFF format is pretty complex and allows a variety of formats and quirks,
>>> which are difficult to support.
>>> I recommend to report the bug at bugs.kde.org, providing a (small) sample
>>> image that cannot be opened by digikam.
>>
>>
>> Would a 1.2MB (1,300,683) file be too large? In my scan program, I set
>> the input on Vuescan from Archive to Web with Scan Resolution set to
>> Auto and that was the smallest size it scanned that Digikam can not
>> read. If I hover the mouse over the image in Digikam it sees the
>> thumbnail (not on the Archive sized ones) but the popup info display
>> shows it cannot find the image dimensions, and Photoshop shows the
>> resolution to be 667ppi with a tiny image size in inches.
>>
>> If I set the Scan Resolution in Vuescan to the lowest in the list,
>> which is 667 - same as above, then the image size more than doubles
>> (3.5MB), but Digikam can see this image normally. I can also set the
>> Scan Resolution to Custom and specify a smaller resolution (for
>> smaller image size) but Digikam sees these images normally. So it
>> seems if I have the Scan Resolution set to Auto in the scanner
>> software then Digikam cannot see the image preview or won't open it in
>> Edit. Digikam behaves normally with images saved to jpeg.
>>
>> I say all this in case it makes it obvious what the problem is, and if
>> not, to see if you think a 1.2 (1.3?) image is too large for the bugs
>> page.
>>
>> thanks, Jim
>>
>
> I may have found a work around as posting this made me think... If I
> set the scanner software's resolution to other than Auto, it seems to
> work. I just have to figure out settings that give my the image size I
> desire. When Quality is set to Archive, with Scan Resolution set at
> Auto, the image is scanned at 4000ppi resolution. Resultant image size
> is around 35MB. If I set the Scan Resolution from Auto to 4000dpi,
> Photoshop still shows image size as 4000ppi, same inch dimensions, but
> the image size has grown to 126MB. But Digikam can see it normally. I
> just don't want to fill up my hard drive quite that fast..
>
> cheers, Jim
>

Ok, maybe last post for the day. In investigating why the image size
went from 36MB to 126MB when changing from auto resolution to 4000.. I
found the the large image scanned at 48 bit depth. If I change that
back to 24 bits, then image size drops back from 126MB to 36MB.
Unfortunately though, Digikam can't read it.

So Digikam can't read auto resolution images or manual resolutions
that show as mode: 8 bits in Photoshop/Bridge, but the ones that show
as 16 bit mode, can be read. So what determines whether Digikam can or
cannot read the files scanned is whether they are set at TIFF file
type: 24 bit RGB (can't read) or 48 bit RGB (can read). So all the
stuff about Auto Resolution vs manually set is moot - doesn't matter.
(Apparently Photoshop image mode 8 bits results from setting Vuescan
to output 24 bit RGB. and Photoshop image mode 16 bit results from
setting Vuescan to 48 bit RGB.)

Is this bug-filing worthy or is there an explanation?

thanks much for your patience..  Jim