When you look through you images, you sometimes want to change rotation (e.g. scanned landscape document). This process is very simple with Gwenview: make your changes and press "Save" button. But there is a big problem with images in TIF format.
Black and white (binary) image in TIFF-format with LZW compression has a very small size. This is preferred format for scanning documents, because a disk space is saving tremendously. But Gwenview ignores the compression type of original TIFF-image and save this file type without any compression at all.
Here is mediainfo output: (I've not found <monospace> tag, sorry)
$ mediainfo ./*
General
Complete name                            : ./OriginalWithLZW.tif
Format                                   : TIFF
File size                                : 52.5 KiB

Image
Format                                   : LZW
Width                                    : 3 508 pixels
Height                                   : 4 960 pixels
Color space                              : Y
Bit depth                                : 1 bit
Compression mode                         : Lossless

General
Complete name                            : ./SavedByGwenview.tif
Format                                   : TIFF
File size                                : 2.08 MiB

Image
Format                                   : Raw
Width                                    : 3 508 pixels
Height                                   : 4 960 pixels
Color space                              : Y
Bit depth                                : 1 bit
Compression mode                         : Lossless

Reproducible: Always

Steps to Reproduce:
1. Open a TIFF-file.
2. Save this file as TIFF-image with alternative name (or change something (e.g. rotation) and save the changes).

Actual Results:  
Check the size of new image -- it's huge!!!

Expected Results:  
Ideally files that are being edited should be saved with preserved compression type (and even compression ratio (e.g. for JPEG format)).