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Barry

Quality Test

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Would you please indulge me with a small test. I have placed two identical images in a slide show, but repeated them 3 times.So, 6 images in all going from A to B to A to B and so on. (no sound)

Which is the best image would you say? A or B

Download Here

 

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Gosh Barry, I had to watch that four times to notice any difference. Perhaps a trip to the optician is required. Anyway, my considered, yet unreliable opinion, is that I prefer 'A'.

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Very difficult to tell but if you concentrate on one part of the image, for example the side of the reddish building on the right, Image A seems to be slightly sharper.  You can see a little more detail.

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Barry

Very little difference but I think that A is sharper. The street lamp centre left, the small square grid-like object just above it and the aerial on the right hand house definitely seem to blur slightly on B. I can't see any difference in colour but A does seem slightly brighter, probably due to being sharper.

Paul

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The slight shift in size is minimal and done so you can see the line as it sweeps across and determines the difference between A and B

Just look at the sharpness and the overall presentation. I am not trying to trick anyone here, but I want some evidence for something I will use in my tutorials and newsletter.

Don't get too technical just look at the two pictures like a non photographer, and pick the best of the two

 

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Yes I thinks so, however I think both images are quite acceptable from an overall presentation point of view. I think if you show these images separately, then It would be impossible to define which is which, most certainly of sufficient quality for the none photographers prospective.

I am right in thinking that this has to do with images size/resolution in slideshows?

 

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Yes,  both images are identical. One is cropped and saved as a jpg level 6 and one is uncropped and saved at level 12

Nothing else whatsoever.

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It depends which one is which and some seem to be having a bit of difficulty with this.

Try this version that simply cuts from one to the other every 2 seconds. Jumping from one to the other may give a better opportunity for you to commit to either A or B as the better of the two

LINK

 

 

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I got to thinking about this issue after a post on another forum where the size of the slide show made was huge. It reminded me of a recent AV competition at my own club where even some non Mp4 slide shows were also massive. I think the records was a PTE slide show at 700MB. I started to wonder how the authors could possibly get their slide shows so large. The issues in making a slide show at 180 MB when it only need be 40 MB are:- Firstly they are harder to transport, especially over the internet. They are harder to post on sites that allow them to be posted. Huge file sizes have caused some less experienced AV enthusiasts to hit all sorts of troubles on their PC, and a huge file may not play very well either, especially on older laptops. 

I set up my experiment to test what I have known for ages. That putting huge files into a slide show when you don't need to can negatively impact the images. Higher resolution images and higher jpg compression levels are unnecessary. It takes a little more work to achieve this, but I will assume that most would take that route if they were confident that they were not throwing away their image quality. Those that can't be bothered are already a lost cause in my book.

The reason I believe many place high resolution images in a slide show and save them at high Jpg compression is that:- Often they are told to by the camera club competition rules and certainly by their camera club colleagues. You have all heard this yourself many times, because if I have you will have too.  Don't save as Jpgs or you will lose quality and if you have to use jpg use level 12. 

The slide show I put up was voted on by 10  people including a couple I showed it to live. 9 voted for image A and 1 for no difference. Under the circumstances I feel it OK to place that vote in the A column. So 10 out of 10 votes for A

The A image was a 1920*1080 image saved at jpg 6. Image B was the original identical image, un-cropped and saved at level 12

Image A would add around 350 kb for each image in your slide show. Image B would add 11.6 MB, but also make the image slightly less sharp and of course the moment you add any animation to that large image, you are also likely to induce the Moire effect. That is 100 times worse than any Jpg compression.  

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I do wonder if people fear discarding their photographic data. Over the year’s camera with bigger and higher resolution sensors have become the norm, with a focus the more megapixels the better the quality of the image.

 

With people spending a fair few bucks to get these megapixels, they feel they have to hang on to them. There is a filmmaker called Ryan Connolly who said that the more megapixels in the camera gives you more latitude in post processing and more to throw away when done.

 

Maybe people have to learn how to do this.

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Morturn

My thoughts exactly. I think what Ryan Connolly probably meant was that if you took an image with a 50MP camera and one with the same camera at 2 MP, then reduced the 50 MP to 2 MP, the image quality would not the same. The image from the 50 MP would be better, when logic says it should not. This comes from my own practical use over many years 

 

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Yes, that’s right, you get a very increased latitude with your image development, which you can then get rid of when done.

It may also just be a matter of confidence too. Now we can see from a practical prospective through this experiment, people may will give it a go.

There are lots of advantages when you reduce image size. Most certainly computers do seem to display better when they are not groaning at the seams processing lager images. File handling also becomes more practical too.

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Many years ago, it has to be at least 20 and probably more, I formed a small on line group called the Internet Digital Imaging Group (IDIG) This was before camera clubs were willing to accept digital photography. So, we formed a group of like minded people and it went from strength to strength. 

One thing I recall from that time was one member bought a very expensive Nikon scanner for his slides and negatives, so that also gives an idea of how long ago it was. In those days of dial up internet the images we circulated on a daily basis were about 800*600 pixels. Yet the images he scanned using that higher resolution scanner stood out even at that size. better quality than the rest of us could manage.It was then that I realized the pixel count is not all about how big you want to print, but that is all you hear whenever you discuss a camera with more pixels.

People think its all about print size, but it isn't.

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I suppose you would need to determine what you mean by print. In my early days in film. 8*10 was the starting size. Most enthusiasts used 16*12 and when you reached a good enough standard to achieve it. 20*16.

In some clubs I have visited over the past few years the print size limit is tiny, rarely above 8*10 and sometimes smaller, yet we have the ability to better anything from the film days now. It reflects the falling interest in printing and if I had to guess I would say 70% of people are non printing and 30% printing, but even that may be a bit optimistic

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