Bug 107154 - presentation output resolution in 16/9 mode seems to be 720p only, need an option to push it at least to 1080p ?
Summary: presentation output resolution in 16/9 mode seems to be 720p only, need an op...
Status: RESOLVED NOTOURBUG
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: Impress (show other bugs)
Version:
(earliest affected)
5.3.1.2 release
Hardware: All All
: medium enhancement
Assignee: Not Assigned
URL:
Whiteboard:
Keywords: needsDevAdvice
Depends on:
Blocks:
 
Reported: 2017-04-14 09:53 UTC by stievenard.david
Modified: 2017-04-27 10:01 UTC (History)
1 user (show)

See Also:
Crash report or crash signature:


Attachments
test presentation with 720p and 1080p pictures (111.57 KB, application/vnd.oasis.opendocument.presentation)
2017-04-26 14:48 UTC, stievenard.david
Details
a spreasheet on screen size / resolutions / pixel densities (32.00 KB, application/vnd.oasis.opendocument.spreadsheet)
2017-04-27 06:31 UTC, stievenard.david
Details

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Description stievenard.david 2017-04-14 09:53:57 UTC
Description:
I was teaching a user about pictures resolution/quality and how to use impress...My advice was in the presentation to use 1080p pictures the products in full screen not more not less so he could get the best out of the customer screen/projector. As we where testing in a meeting room I discovered that the 1080p pictures were bigger then the slide size forcing him to resize pictures.
So it looks like the output resolution of impress is in 720p

Tested on libre office 5.1.3 on win10x64 / linux kde neon => same result


To get the best out a projector or a screenwall impress should be able to display 1080p pictures so 1pixel in the picture = 1 pixel on the screen


I searched for options about the resolution of the slide, it is seems possible to make it bigger when tweaking the size in centimeter but centimeters make no sense on a screen

Steps to Reproduce:
1. create a picture in 1080p (1920*1080pix) and in 720p (1280*720pix)
2. open impress and configure the slide layout in 16/9 with menu / slide / slide property / "page" tab
3. insert both pictures in the created presentation in two different slides
4. right click on each pictures / "original size"

Actual Results:  
the 1080p picture is bigger then the slide so I have to manually resize it down
the 720p picture is almost the same size as the slide

Expected Results:
the 1080p picture should be at large as the slide
720p should be smaller



Reproducible: Always

User Profile Reset: No


Additional Info:


User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0
Comment 1 Buovjaga 2017-04-26 11:32:13 UTC Comment hidden (obsolete)
Comment 2 stievenard.david 2017-04-26 14:48:31 UTC
Created attachment 132865 [details]
test presentation with 720p and 1080p pictures

actually I can't reproduce exactly the case I have with the previous presentation

720p image was fitting the presentation backgroup and 1080 was a bit bigger, now both of them are even bigger.

is there a way yo control the resolution of the background ?
Comment 3 Buovjaga 2017-04-26 17:40:48 UTC
Ok, I apparently missed step 4 before.

Not really sure, if it's worth the effort, but you could tweak the centimeters to reach some goal. You have think in terms of "pixels per centimeter" or pixels per inch aka DPI. Then you have to decide, what your desired DPI value is. Resize the page in centimeters and then resize the picture.

I can ask for developer input to make sure what is the reality here.
Comment 4 stievenard.david 2017-04-27 06:28:48 UTC
tell me if I'm wrong but 

resolution :
- is an absolute value :
- it's the number of pixels in x and y
- it's expressed using this notation X * Y
- if the pixel aspect ratio is it drives the media ratio aspect, if x/y = 16/9
- classic resolutions in 2017 are 720p=1280*720 px / 1080p=1920*1080 px / 4k=3840*2160 px


pixel density :
- is a relative value :
- it's the result of the resolution applied to a physical support : screen, paper...so it depends on the physical support
- it's express in DPI (dot per inch) or PPI (pixel per inch)
- it's basically giving you the size of each pixel resulting of the number of pixels in the source media applied to the support



I had a 2nd look at the compress image menu and it's quite confusing (on an image, right click / compress...)

"resolution"
- bellow the width and height there is "resolution" expressed in DPI, this is wrong, this is pixel density.
- Pixel density depends on the physical support, I choosed 16/9 screen, how impress can give me a pixel density if I don't specify the size of the support ?
- Why would someone use the pixel density ?
  - it seems to me quite impossible to predict on what support I'll have to show the presentation
  - pixel density is interesting value when combined with the distance of viewing (large LCD screen have very low dpi but from far away it's ok) so this is irrelevant for a presentation in a meeting room where in 2017, a 16/9 "screen" will be 720p 1080p or 4k anyway. so the maximum picture quality you can get out of the presentation is to have : 1 pixel on the picture = 1 pixel on the screen


I think I have the explanation of this : it seems that these calculations are based on the "slide paper size" (available in slide properties) and when you select : screen 16/9" the default size of "virtual 16/9 paper" is 28cm*15.75cm 


1/ question
when using a 1920*1080px picture on a 1080 display will impress display this picture in it's native resolution ?


2/ suggestion
work with resolutions, a nice feature could be able to correct all pictures in one click. For that you'll need
- to set the presentation resolution
- picture resolution
- a picture quality setting
- the position on the screen
Comment 5 stievenard.david 2017-04-27 06:31:38 UTC
Created attachment 132881 [details]
a spreasheet on screen size / resolutions / pixel densities

to illustrate my previous comment
Comment 6 Buovjaga 2017-04-27 07:58:45 UTC
I asked about this on the developer IRC chat and Thorsten said:
slide dimensions are measured in cm/inch, not pixel. picture sizes & positions are not pixel, likewise.

and then everything gets scaled to fit the screen, whatever pixel resolution that has...

Closing this as notourbug.
Comment 7 stievenard.david 2017-04-27 08:27:33 UTC
a presentation is made to be displayed on a screen, not printed

so talking in centimeters or in pixel density makes no sense
Comment 8 Buovjaga 2017-04-27 10:01:02 UTC
(In reply to stievenard.david from comment #7)
> a presentation is made to be displayed on a screen, not printed
> 
> so talking in centimeters or in pixel density makes no sense

But we talk about pixel density in the context of screens, so it does make sense: http://pixensity.com/list/desktop/