On 29 Sep., 22:18, JPW <[email protected]> wrote: > > Ooops... my fault. I did mean you should set exposure sigma to 50, not > > exposure mu. I gave you a mixed message: > > OK. Appreciate the correction. > I had deduced this was your intent after your response when I reread > your original post and the manual.
Sorry again for the confusion and the harsh tone. > Although complex, I actually do understand the concepts (the graphs in > the manual are helpful.) My real problem is knowing exactly what to > use as commands and how and where to enter them. This is where I have > difficulty using CLIs — I understand their incredible power and > simplicity makes them desirable, but I'm a terrible speller with > dyslexia, and my brain just doesn't work well with text based > abstraction. Hugin started out as a GUI from which to operate a bunch of command line tools. A lot of this heritage is still apparent, and keeping the components separate also has certain advantages, i.e. each can evolve by itself and be used individually and by other projects as well. The helper programs, like nona for 'warping' and enblend/enfuse for combining the warped images, ar CLI-driven. Since for most purposes it's perfectly sufficient to use them with their default settings, probably noone has made an effort to present their interface graphically. Only when people try and do things out of the ordinary, additional parameters become necessary. Trying to keep a GUI consistent with the moving targets (--exposure-mu and --exposure- sigma, for example, are quite recent. if I remember correctly) takes someone to do it - hugin has rather slim resources, and there are a lot of more pressing needs. You'll just have to bear with this status quo for now. > Anyway, I deduced from your posts that I should put > --saturation-weight=0 --exposure-sigma=50 > in the enfuse options box and check > "Panorama Outputs" Exposure fused from stacks" > Is that correct? correct. > If it is correct, I did run some experiments with various sigma at . > 25, 5, 25, & 50 so I could observe the effect. Assuming they ran > correctly— again, where can I review a log to see exactly how they > ran? > They all looked equally good to me In terms of noise reduction and far > superior to any of the jpegs or tiff. Should there be a great deal of > difference between them? The difference between any of your large figure trials should be minimal, but there should be a measurable (if not immediately noticable) difference to the default of .25 - since you've had a look at the gaussian curves in the manual, imagine that doubling the sigma widens the curve to double breadth, so your lowest try at 5 is already 20 times as wide as the default, and a further increase to 50 does not make much of a difference, just as incresing it further to 500 wouldn't either. > I looked particularly in the blacks and in > the glossy areas. The light glossy areas in the originals had the most > obvious sensor noise. The jpeg crud was distributed everywhere pretty > liberally. This was all disappeared with the default settings. Change > in sigma seemed to have little effect. Again, perhaps this is because > of the nature of my test images. Perhaps they were so noisy even a > small sigma repaired the majority of the noise. Or perhaps a high > sigma might produce a more obvious effect using only 2 or 3 input > images (I used 5.) It does depend on the level of noise and the peak intensities. If you've one image withe a bright pixel where the correcponding pixels are dark, this pixel is closest to well-exposedness and would be weighted as 'best' - not what you want, that's why you raised the sigma to 'cloud' enfuse's judgement. The more images you have, the less obvious the effect of one brighter pixel becomes, since all images are still included in the result, even though the less well- exposed are included less. Using enfuse with the default settings does, as you observed, help some, but the increased sigma should make the effect better. This may be hard to appreciate with the naked eye. Try this: Load the result from the default settings and that with increased sigma as layers into an image processor. Set the layer mode to 'difference' and then flatten the image. It will look pretty much black at first glance now, and this demonstrates how small the difference is - it's hard to see with your naked eye. Next, set the levels so as to have the white point quite low down (lower quarter or less, just play with it) to brighten the difference image. You'll now see the difference between the two versions magnified, and I'm quite confident the differnce will look quite noisy and show how the added parameter worked. You also have to take into account that warping the images (like, shift them all so that they precisely overlap) will already reduce the noise a bit, since the pixels in the warped images will already be put together from several original pixels by the interpolation stage. And to appreciate the denoising effect fully, you should have the output at 'optimal size'. If you really want to have a closer look at problem areas, set the output crop to that area (in the openGL preview) and select a larger-than-optimal output size in the stitcher tab. It'll work like a magnifying glass. And while going on about the exposure sigma all the time, it is equally important that you should set the saturation weight to zero, as you have done (and as I managed to convey to you without any typos ;-) - often the noise isn't only of varying brightness, but also of varying coulour. Having enfuse judge a pixel best just because noise made it more saturated isn't what you want either, and the default settings use the saturation as quality criterion as well, though less so than the exposure. > Thanks again. > If you would like to see the test images, let me know. No thank you. I'm quite confident all is as I say, and I'm also off for a bit of a holiday today, so I could only look at them once I'm back - when I'll have plenty of my own to look at and you'll probably be an enfuse expert. > > ... > BTW, > This is a very nice explanation. Thanks. Did you follow up the links from the Wikipedia article I recommended? I think that http://research.edm.uhasselt.be/~tmertens/papers/exposure_fusion_reduced.pdf is really an excellent explanation of the process. Once you grasp the concepts, it all falls into place. And there are a few GUIs for enfuse as well - try and browse for 'enfuse GUI' - with which you can more playfully explore the parameters. Kay -- You received this message because you are subscribed to the Google Groups "Hugin and other free panoramic software" group. 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