Question:-Grid appearance on some images

[RoseW Profile Private messageWebsite]

When playing back an mpg production saved for use with a computer and projector I notice on 'some' images a grid like appearance in one area; not over the whole image.
Its like a fine wire mesh (Almost as though the monitor screen has a grid back there)
I thought it might be a signal that the older laptop was struggling. I bought a new laptop...it was a good excuse.
BUT just created a new show and on the big desktop on some images in the 26 min project this grid patch shows up.
I increased the bit rate to 15000 but did not change the frame rate in the custom settings for the mpg and that patch of grid still appeared on the desktop and new laptop monitor. Both have a standalone video card.

No ordinary person viewing will likely notice because its a quick-likely just as the slide fully loads and before the transition starts.
Since its only a couple of images and I have used images that originate since 2008 I wondered if older images from another camera model might be a factor. I didn't change the older images to the current Lightroom v4.4 process. BUT it doesn't happen consistently. Out of 314 images it might be a maximum of 3 here and there.

I'm just wondering what it is and if I need to be doing something that accommodates this little appearance.

Rose

[BarbaraC Profile Private messageWebsite]

The only thing that comes to mind is a moire pattern caused, basically, by an "argument" between lines in the image and scanning lines on the screen. It can sometimes be reduced by blurring the area slightly, but truth be told, I've never had much success with it. It just looks a bit blurry.

It used to be that, on TV, people weren't supposed to wear stripes, particularly thin ones, because it could turn into a flickery mess on the screen, but they've been emboldened by HD and are paying less attention to it even though it definitely still happens.

Barbara

[gpsmikey Profile Private message]

I'm with Barbara on this one - the images in question were not pictures of a screen (TV/computer) by any chance were they ? The other way is to have a digital image that you have really cropped down so that you again run into the same issue (because the pixels are big relative to the image due to the crop). Generally, though, if it is a moire problem, the "grid" or lines you see will not be straight because it seldom works out that everything is at right angles to everything else. If the grid pattern is perfectly straight and evenly spaced, I would have to think it was somehow added to the slide, but I'm not aware of anything that would do that. I would suspect the graphics card as a possible issue, but you have changed computers/graphic cards, so that pretty much eliminates that. You have verified that the original image used in the slide does not have this issue if you zoom in on it ?

edit - in re-reading the original post, you say it only shows up in some areas of the image, not the whole image - that again has the moire feel to it. Here are a couple of links to check out - see if they describe what you are seeing:
http://en.wikipedia.org/wiki/Moir%C3%A9_pattern
http://photo.stackexchange.com/question ... e-avoid-it


mikey

[RoseW Profile Private messageWebsite]

Thanks for the Moire input.
I hadn't thought of that and its presence is likely connected to older images.
There is a moire correction brush in Lightroom so I'll have to keep that in mind if I see it again. I'll zoom up and down quickly in Lightroom to see if it momentarily displays.

The presence of this 'grid/lines' (moire) moment is only in a portion of the image such as petals that are out of focus on a bloom. Its not in a major feature so I might get away with slightly blurring that background area.

These are horticultural group presentations with an emphasis on blooms or garden scenes so I'm selecting the images with good colour, contrast and sharp focus but often the background is not in focus and that is where this 'moire' is occurring.

Thanks again and in particular for the speedy response

Rose

[gpsmikey Profile Private message]

This is one area where digital is not necessarily better than film. Film had a random grain pattern and as such, when you were working with things that consisted of lots of dots etc, you didn't see the interaction. On the other hand, take a picture of a new flatscreen TV with your digital camera then zoom in and out on the display on the back to view the image - all sorts of interaction between the dot spacing on the tv, the dots in the sensor and the dots in the display on the camera. You can also run into that scanning images that were printed on a dot matrix printer etc. There are days I want my old fine grain B/W film, Microdol-X and fixer back

mikey

[BarbaraC Profile Private messageWebsite]

There are days I want my old fine grain B/W film, Microdol-X and fixer back

We still have our SLR's, bulk film, enlarger et al, paper, and chemicals (probably not good anymore ) down in the basement darkroom/laundry. We look at these things with yearning, but digital is so much handier, easier, and it doesn't envelop a person in stinky darkness for extended periods. I wanted to sell all of it, knowing it will never be used again, but the son refuses to believe this, claiming he'll one day go back down there. Sure.

Barbara

[gpsmikey Profile Private message]

Yeah, I still have a lot of my stuff too - not likely to be able to sell it for another few years at which point it will become a true antique and maybe worth something I do miss watching for that image to begin to fade in in the developer tray though. You only had to try a couple of times to load one of those plastic tank reels when damp with a 36 exposure roll of film before you went out and purchased a stainless steel tank (you could load those wet). Then there was always the thrill of dropping the roll of film and spending time on your hands and knees in the dark trying to figure out where that canister went .... wanna buy a good enlarger ??

mikey

[BarbaraC Profile Private messageWebsite]

Mikey, you and I could probably spend several hours trading tales of glory and defeat in the darkroom. Ever have a partner in that small, dark space? Nothing like having an argument when trapped. I mean, you can't simply trounce out of there in a huff.

Barbara

[gpsmikey Profile Private message]

Been there, done that (but other things are possible there too )

mikey