[Xerte] Re: FW: jpgs degrading - is this a new phenomenon?

[Ron Mitchell]

Hi Alistair

This is all quite predictable and not a server or flash player issue - just
a simple fact of viewing raster images at different to actual size. Your LO
is set to full screen try switching to default so it's 800 x 600 and you'll
see that some pages look better at that size and others look better at full
screen? 

 

It wouldn't help with all your images but for the example here what about
using the Charts > Table page type e.g.
http://itq.jisctechdis.ac.uk/xerte/play_85

HTH

Ron

 

From: xerte-bounces at lists.nottingham.ac.uk
[mailto:xerte-bounces at lists.nottingham.ac.uk] On Behalf Of Alistair McNaught
Sent: 14 January 2012 17:45
To: Xerte discussion list
Subject: [Xerte] Re: FW: jpgs degrading - is this a new phenomenon?

 

A final version with 3 pairs of images (jpg v png) at  sizes 300, 360 and
550 respectively. In all cases jpgs show significant degradation. PNGs only
show degradation at the 550 px point where they are being shrunk from 550 to
470 to fit the space.

 

In the short term I'll stop using jpegs in favour of pngs and gifs but in
the long term I'd be really interested to know why jpegs fare so badly. They
will be the format of choice for a lot of less technically inclined users so
if it ispossible to determine whether the code has changed and if so to
change it back I'd be very grateful. 

 

That's all the excitement needed for one weekend - I'm signing out now!

 

All the best and thanks for the rapid responses Dave and Pat.

 

A

 

From: xerte-bounces at lists.nottingham.ac.uk
[mailto:xerte-bounces at lists.nottingham.ac.uk] On Behalf Of Pat Lockley
Sent: 14 January 2012 17:08
To: Xerte discussion list
Subject: [Xerte] Re: FW: jpgs degrading - is this a new phenomenon?

 

It looks like XOT is stretching them, and so is having to fill in bits
(which is degradation via interpolation, which sounds redundant but lacking
the words to find a better one - negative amelioration?)

 

The originals are fine.

 

What's the maximum size? 640 something?

On Sat, Jan 14, 2012 at 5:02 PM, Alistair McNaught
<Alistair.McNaught at heacademy.ac.uk> wrote:

Hmmm - here's the test I did for Pat:

First 2 slides of http://itq.jisctechdis.ac.uk/xerte/play_82 show
significant quality difference yet the image below shows they are virtually
identical in their raw form.

 



 

Curiouser and curiouser..

 

 

 

 

From: xerte-bounces at lists.nottingham.ac.uk
[mailto:xerte-bounces at lists.nottingham.ac.uk] On Behalf Of Dave Burnett
Sent: 14 January 2012 16:56
To: Xerte list


Subject: [Xerte] Re: FW: jpgs degrading - is this a new phenomenon?

 


>does it look equally blurry on your PC on that slide? 

 

Yes.

 

Vista/Chrome

 

 

  _____  

From: Alistair.McNaught at HEAcademy.ac.uk
To: xerte at lists.nottingham.ac.uk
Date: Sat, 14 Jan 2012 16:48:14 +0000
Subject: [Xerte] Re: FW: jpgs degrading - is this a new phenomenon?

Hi Dave / Pat - thanks for quick responses

Yes these shots are all on same laptop - it appears to be a new problem. 

The only PCs I have access to are all the same spec but I'd be interested if
it looks different on other people's PCs - for example the LO I first
spotted it on yesterday is at 

http://itq.jisctechdis.ac.uk/xerte/play_79 and page 14 is a slide show
navigator. Slide 4 on page 14 is shown below as it renders for me and the
original image is also shown superimposed. Notice how the table has become
blurry. It wasn't always like that .. does it look equally blurry on your PC
on that slide?

 



 

 

Alistair

 

 

From: xerte-bounces at lists.nottingham.ac.uk
[mailto:xerte-bounces at lists.nottingham.ac.uk] On Behalf Of Dave Burnett
Sent: 14 January 2012 16:36
To: Xerte list
Subject: [Xerte] FW: jpgs degrading - is this a new phenomenon?

 

Sorry, those are both on the same screen aren't they.

 

How about Flash version then?

I'm just wondering if they way Flash handles the rendering.

Same effect on a different machine?  

 

 

From: d_b_burnett at hotmail.com

To: xerte at lists.nottingham.ac.uk

Subject: RE: [Xerte] jpgs degrading - is this a new phenomenon?
Date: Sat, 14 Jan 2012 11:28:37 -0500

Latest video drivers?

 

 

  _____  

From: Alistair.McNaught at HEAcademy.ac.uk
To: xerte at lists.nottingham.ac.uk
Date: Sat, 14 Jan 2012 16:26:22 +0000
Subject: [Xerte] jpgs degrading - is this a new phenomenon?

This seems weird but yesterday I was demonstrating a learning object to some
colleagues I was working with and I noticed that the images which I'd
carefully crafted to be crisp and sharp and fit the available space were
looking pixellated and ugly with lots of jpegy artefacts (like when you save
a jpeg at too coarse a setting and get fuzz around lines etc). The originals
I uploaded are much higher quality. 

 



 

 

However no such degradation is apparent with PNG files as shown below: (as
before the original is at the bottom and the Xerte rendered version at the
top). In this case the quality is indistinguishable.



 

 

Is something taking place in the upload that degrades the jpgs or how is
this oddity explained. For the short term I can use PNGs rather than JPGs
but it introduces an extra work layer and It doesn't help the dozens of LOs
that used to look crisp and now look fuzzy. Any suggestions gratefully
received!

 

A

 

 

 

 

 

Alistair McNaught

Senior Advisor 

JISC TechDis

C/O The Higher Education Academy Building

Innovation Way

York Science Park

YORK

YO10 5BR

 

07870567659

Skype: alistair_techdis

 
<http://www.jisctechdis.ac.uk/?utm_source=emailsig&utm_medium=email&utm_camp
aign=sitelaunchmail> http://www.jisctechdis.ac.uk 

http://www.scoop.it/t/inclusive-teaching-and-learning 

 

Interested in pragmatic inclusion- focused staff development?  
See JISC TechDis
<http://www.jisctechdis.ac.uk/techdis/pages/detail/floating_pages/ITQ_Access
ible_IT_Practice> ITQ for accessible IT practice information and
<http://itq.jisctechdis.ac.uk/mod/resource/view.php?id=5> taster resource. 

 

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