Inserted images move from their place

[BasePlayer]

I have a large document (500 pages) with a number of inserted images. Generally I struggle to keep the images where I have inserted them. Typically, if they are landscape, I have them centred and anchored to a paragraph. This usually works, but sometimes they jump on to the next page for no apparent reason. But where I have portrait format images, I prefer to place them against the outside margin, and find that the best way to make them stay there seems to be to anchor them to the page. Neither method seems to be 100% reliable, and I have to constantly checked that my images haven't moved while editing the text.
However, my big problem arose after splitting the document in two to speed up the editing/saving process. Everything was okay-ish (although I still had to check the odd image), until I tried to rejoin the two halves of the doument. Now I find that an image linked to, say, page 10 in the second half document, turns up on page 10 of the first half. I had a look to see if the page number was stored somewhere in the image format dialogue, but can't find it.
I have also worked my way through the helpful tutorial "Some useful hints on using images", but don't see this particular problem addressed.
I have also downloaded (belatedly) the extension to compress images. The notes suggest compressing the image when inserting, but I can't see a way of doing this.
I may have to work through the whole document reinserting the images that have moved, but any help or suggestions will be welcomed.

[erbsenzahl]

best way to make them stay there seems to be to anchor them to the page.
...
Now I find that an image linked to, say, page 10 in the second half document, turns up on page 10 of the first half.

Hi,
for that reason you should not anchor images in subdocuments of master documents.

Anchoring images
An image (graphic) anchored To page in a subdocument is not displayed in a master document.
Because the master document reorganizes the page flow, page numbers, and cross-references
when it collates the subdocuments, the image loses its anchor reference and disappears.
In contrast, an image anchored To page in a text section of a master document stays with that
page and does not move if the length of subdocuments changes. The image may end up on a
page somewhere in the middle of a subdocument, not where you want it to be.
Note
The anchor “to page” is deprecated. Avoid using it.

For other advices explain more details of anchoring and wrapping images in your text. As you have stated this is a complicated theme.

In my texts I anchor images as often as possible As Character (no wrapping). Other anchoring (To Character; To Paragraph) are sometimes a bit fiddly (especially near page breaks).

[BasePlayer]

Thank you for your reply. I'm considering keeping the two halves separate, making a PDF of each, and then combining the PDFs.
Any advice, anyone, on how to compress an image when inserting it (I have downloaded the extension)

[erbsenzahl]

General advice: Link images, it's handier than to embed them.

how to compress an image when inserting it (I have downloaded the extension)

If you have installed PixCompress (via menu Tools | Extension Manager...) it will display in menu Tools | Minimize pictures... When set to work it will compress all picures (but you can't choose the ratio of compression). You better link images instead of embedding them.

If you have linked (and not embedded) the images this wouldn't be a problem: When exporting your Writer file to PDF you can choose the image resolution. AFAIK you can reduce the resolution (e. g. to 300 for printouts) if the original resolution is higher than the output. But images with lower resolution cannot be increased in it.

Tip
To extract and link images in Writer you have to use LibreOffice's PicExtract extension. For further working on OpenOffice you can save a file in LibreOffice in ODF format version 1.2 Extended - or work generally on LibreOffice .

Godspeed

[RoryOF]

I would not regard 500 pages as a "large" document; of course, this depends on the number and size of the images. War and Peace, which is probably as large a book as most will ever need, amounts to 568,000 words (give or take a few hundred words!) and 2750 A5 (approximately US Brochure) pages.

It is important to size your pictures before inserting them into OpenOffice; typically they should be no more than 210 dpi, but many will use 300 dpi as a more readily available setting. The difference in quality between 180 dpi and 210 dp will probably not be noticeable in photographic images; line images can be of a higher resolution. All images should also be adjusted to the correct size before being inserted into an OpenOffice document.

[robleyd]

As you are using Windows, you might consider IrfanView for pre-processing of your images before inserting them in your document.

[John_Ha]

See the Writer Tutorial: Some useful hints on using images.

Your moving images means the program is working as designed. You need to understand the difference between Anchor to a page ..., and Anchor to a paragraph.

If you Anchor an image to, say, page 7 and you add three pages of text before page 7, the image will stay on page 7 and the text it was nearby will move to page 10.

If you Anchor an image to a paragraph on page 7, and you add three pages of text before page 7, the text on page 7 and the image anchored to it, will flow to page 10.