Without anakysing the document (only from the screeshot), your image is inside a frame and some padding space is allotted around the image (can be modified in image properties,
Also, you image may be cropped. See
Crop tab. A different scale factor may apply to height and width.
Finally, have a look at
Type tab and the Size parameters, notably Keep ratio.
If this doesn’t allow you to cure the issue, attach a sample file with the problematic image to your question (not to an answer which wouldn’t be a solution to the problem).
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In case you need clarification, edit your question (not an answer which is reserved for solutions) or comment the relevant answer.
EDIT 2020-11-04 - Answer to Dadasaur
Your sample file has several problems:
- wrong choice of anchor mode for the image considering its dimensions
- wrong size for the caption frame
- presence of a nonsensical drawing object
Apparently, drawing object Frame4 (not a frame at all) is not related to anything and can de deleted without changing document semantics.
Image Image4 (original size 40×26 cm) is scaled down 44% (to 17.6×11.4 cm) but is give a size of 17.6×3 cm in the
Type tab. It is anchored
As character which is an error with such a large picture. Being a character, wrap mode is pointless.
The consequence of these inconsistent settings is an area of 17.6×11.4 cm is reserved for the “character” but it is cropped to the first vertical 3 cm. Hence the red triangle for clipped content.
A caption has been added to the image-character (which is nonsense because a paragraph, the caption, cannot be inserted inline within another paragraph; it can only follow another paragraph) causing creation of frame Frame5 with dimensions 17.6×3.37 cm which is clearly too small. The previous inconsistencies prevent the caption to be visible.
Change image anchor mode to To paragraph, wrap mode to None without Allow overlap. In
Crop, restore both Scale factors to 44%.
Change Frame5 properties to AutoSize in
Wrap mode to None without Allow overlap.
As a general rule, be very very cautious with large images.