Digikam-users Digest, Vol 241, Issue 4
Carol C. Kankelborg
cckborg2 at kankelborg.net
Sun Jun 8 05:45:18 BST 2025
Steve,
Most of that makes sense. I noticed the height/width dimension switch. The smaller file appears to have been rotated by DigiKam 8.1.0. That is the one I put in the vacation album, so if it needed rotating, it makes sense I would have done that.
I am presently using 8.6.0. Is 8.6.0 smart enough to note rotation when displaying the image but 8.1.0 was not? The larger image has the same orientation when I look at it in DigiKam (Similarity tab).
For software that rotates images (in this case I assume it was DigiKam 8.1.0), is the quality (and size) of the rotated image diminished because it had to be uncompressed, rotated, then re-compressed? If so, is it a serious degradation or should I not worry about it for JPG photos of vacations? If not, why would one be smaller than the other? Is it just the way the JPG compression works that portrait images are larger than landscape?
Thanks for your answer,
Carol
> On Jun 4, 2025, at 11:08, Steve Franks <stevef48 at gmail.com> wrote:
>
> To my eye it looks as though one of the images has been rotated through 90°. That would alter the file size.
> Some software rotates images, other programs take note of the rotation when displaying the image.
> I hope that makes sense,
> Steve
>
> On Wed, 4 Jun 2025 at 12:00, <digikam-users-request at kde.org <mailto:digikam-users-request at kde.org>> wrote:
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>> Today's Topics:
>>
>> 1. Which image to keep -- Similarity scan and different file
>> sizes (Carol C. Kankelborg)
>>
>>
>>
>> ---------- Forwarded message ----------
>> From: "Carol C. Kankelborg" <cckborg2 at kankelborg.net <mailto:cckborg2 at kankelborg.net>>
>> To: digikam-users at kde.org <mailto:digikam-users at kde.org>
>> Cc:
>> Bcc:
>> Date: Tue, 3 Jun 2025 20:08:26 -0600
>> Subject: Which image to keep -- Similarity scan and different file sizes
>> I ran the Similarity tool with range 99–100% across my whole library. It detected some photos that differ in size, but it is not clear to me which to keep. I must have imported them directly from my camera (Nikon D5600) twice at different times. I moved one to an album of photos from my vacation and the other I left in the album it was imported into. I don’t understand why they would have different file sizes.
>>
>> The newer import file that I put into the vacation album is larger than the older one. I zoom in as far as I can in Preview mode and flip back and forth between the two photos and cannot detect a difference, suggesting the JPG compression is the same.
>>
>> Here is the result of doing an exiftool comparison between one pair of images. In DigiKam, it lists the Size for the larger image as 14.1 MiB (14,756,434) and the smaller as 12.3 MiB (12,873,885), which do not match the sizes from exiftool.
>>
>> I would rather keep the file already in the vacation album, but not if it has a lossier compression than the larger file. I welcome any explanation for what I am seeing and what the reason for the file size might be.
>>
>> Thanks,
>> Carol
>>
>>
>>
>> Shalom-cckborg $ exiftool -diff CCK_7897.JPG ..//Camera\ Import/2024-08-15/109D5600/CCK_7897.JPG
>> ======== diff < ..//Camera Import/2024-08-15/109D5600/CCK_7897.JPG > CCK_7897.JPG
>> < [System] Directory : ..//Camera Import/2024-08-15/109D5600
>> > : .
>> < [System] File Size : 15 MB
>> > : 13 MB
>> < [System] File Modification Date/Time : 2023:11:17 10:38:32-07:00
>> > : 2023:11:19 17:07:02-07:00
>> < [System] File Access Date/Time : 2025:01:18 04:53:40-07:00
>> > : 2025:01:18 21:36:07-07:00
>> < [System] File Inode Change Date/Time : 2025:01:15 21:31:46-07:00
>> > : 2025:01:06 20:01:39-07:00
>> < [File] Image Width : 6000
>> > : 4000
>> < [File] Image Height : 4000
>> > : 6000
>> < [File] Y Cb Cr Sub Sampling : YCbCr4:2:2 (2 1)
>> > : YCbCr4:4:0 (1 2)
>> > [File] Current IPTC Digest : 1e94c722fc098f69f3aa0d01b303732c
>> < [IFD0] Orientation : Rotate 90 CW
>> > : Horizontal (normal)
>> > [IFD0] Processing Software : digiKam-8.1.0
>> > [IFD0] Image Width : 4000
>> > [IFD0] Image Height : 6000
>> < [ExifIFD] Exif Image Width : 6000
>> > : 4000
>> < [ExifIFD] Exif Image Height : 4000
>> > : 6000
>> < [IFD1] Thumbnail Offset : 18296
>> > : 18284
>> < [IFD1] Thumbnail Length : 9886
>> > : 4909
>> < [MPImage2] MP Image Start : 13713920
>> > : 13661039
>> < [MPImage3] MP Image Start : 13812224
>> > : 13759343
>> < [Composite] Image Size : 6000x4000
>> > : 4000x6000
>> > [XMP-x] XMP Toolkit : XMP Core 4.4.0-Exiv2
>> > [XMP-tiff] Image Width : 4000
>> > [XMP-tiff] Image Height : 6000
>> > [XMP-tiff] Orientation : Horizontal (normal)
>> > [XMP-tiff] Software : digiKam-8.1.0
>> > [XMP-exif] Exif Image Width : 4000
>> > [XMP-exif] Exif Image Height : 6000
>> > [IPTC] Originating Program : digiKam
>> > [IPTC] Program Version : 8.1.0
>>
>>
>>
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