Apache OpenOffice Community Forum

When saving a drawing as .png, what is the best way to obtain a smaller file size (from say 42Kb) while retaining the same pixel size (say 600x600)?

Obviously there may be some loss of resolution,
Thanks,
Dave.

If you want to keep the same pixel count the only way is to reduce the colours from 24 bit to 8 bit, or even 4 bit or 2 bit. See the tutorial on images or save the PNG as a GIF which reduces it to 8 bit colours.

Why do want to do it? A 42kB image is tiny.

Hi John Ha.
Reducing the colours seems worth trying, how do you "reduce the colours from 24 bit to 8 bit"? Can't seem to find the settings for that.
Thanks,
Dave.

It's all in the Tutorial. See [Tutorial] Some useful hints on using images.

Yes, I have read through it but couldn't find how to reduce the colours.
I'll look again ...

7. Use 256 colour (8 bit) images instead of 16 million colour (24 bit) images if possible

In IrfanView go Image > Decrease colour depth.

If you have scanned an image of a page, the white background will be many different shades, all close to, but not exactly [255,255,255] or [128,128,128]. Use Replace colour and set a tolerance of 20 or more - this makes all the "almost white" exactly white. As the values are now all identical they will compress much more.

I cannot find anywhere in Open office "Draw" to reduce colours and the tutorial recommends IrfanView as well.
Found that setting "Interlaced" off reduces file size. Doesn't seem to affect the image though.
Thanks.

Reducing the colours seems worth trying, how do you "reduce the colours from 24 bit to 8 bit"? Can't seem to find the settings for that.

It is NOT an Apache Openoffice feature. You must use a third party pixelgraphic editor or manager software for this task - before you embed the image into an OpenOffice document.

Thanks Zizi64, that'll explain why I couldn't find it !

Hi everyone,
If you’re looking for an easy way to compress PNG images without losing quality, you can try third party online tools like this PNG Compressor. It’s free and works great for reducing file sizes while keeping the original resolution.