Beginner's guide to stacking planetary images with AutoStakkert!2

[egidio]

I'm reading on several websites that mjpeg is good for planetary imaging...an i safe?!?!? =D

[JamesF]

MJPEG is definitely not good for planetary imaging.  JPEG is (sometimes very) lossy, so you'll struggle to get a decent image out of it.

James

[egidio]

• Uhm ok...then I'm gonna have to still use avchd and convert it into avi without losing quality. Another thing: I've read that PIPP accept avchd but when I tried to import the file there it just says I can't...any suggestion?

[egidio]

also i really don't understand why mjpeg is lossy? from what i'm reading everywhere an mjpeg avi has quality:

"In multimedia, Motion JPEG (M-JPEG or MJPEG) is a video compresison format in which each video frame or interlaced field of a digital video sequence is compressed separately as a  JPEG image" ...isn't great for stacking?

[JamesF]

AVCHD is, as far as I'm aware, layered on top of MPEG.  If you take a raw video frame, convert it to MPEG and then convert it back you won't get what you started with, so data has been lost.

JPEG is poor in two ways.  First it's 8-bit only, so if you have more than eight bits of data they'll get thrown away.  Second it's lossy compression.  In my experience MJPEG is generally used where there's insufficient bandwidth for the full frame even with lossless compression, so the raw frame to JPEG conversion will be lossy too.  In fact, if you look up JPEG on Wikipedia the first sentence says "JPEG ... is a commonly used method of lossy compression".

Thinking about the way that JPEG actually works at an algorithmic level and how stacking works it seems highly unlikely to me that JPEG images are ever going to stack as well as raw frames.  If you think of stacking as a process for reducing the random element of noise then I think it might not be unreasonable to view JPEG conversion as actually modifying the noise in a manner that makes it harder to reliably remove the random component.

James

Edited December 28, 2014 by JamesF

[egidio]

well, all i have is avchd =( I've seen that many of u use PRISM VIDEO CONVERTER, which is fortunately supports AVCHD (.mts) ...do u think prism is great to convert into avi??? whichc quality will i have?

[JamesF]

I don't use it, so I'm afraid I can't help with that one.

James

[egidio]

it says that will convert into avi .264, is it good? =D

[egidio]

I mean H.264

[JamesF]

H.264 is MPEG4 I believe.  It's almost always lossy compression too.

Unless you can find out exactly how the camera firmware works and decide what format you want from that I think you might just have to accept that you're never going to get stunning results this way and work on the things you can change, such as accuracy of focusing

James

[egidio]

H.264 is MPEG4 I believe.  It's almost always lossy compression too.

Unless you can find out exactly how the camera firmware works and decide what format you want from that I think you might just have to accept that you're never going to get stunning results this way and work on the things you can change, such as accuracy of focusing

James

ok than can u suggest me into what type of avi i have to convert my file? i mean, which codec should i use?

[cgarry]

• Uhm ok...then I'm gonna have to still use avchd and convert it into avi without losing quality. Another thing: I've read that PIPP accept avchd but when I tried to import the file there it just says I can't...any suggestion?

PIPP should support avchd files, it certainly does for all the files I tested.  What is the error you are getting?

Thanks,

Chris

[egidio]

I've seen that u import a dib file into pipp, which is the same codec of the output...i will try some converter that can do avchd into dib then

[egidio]

PIPP should support avchd files, it certainly does for all the files I tested.  What is the error you are getting?

Thanks,

Chris

yeah it should, but look:

[cgarry]

I've seen that u import a dib file into pipp, which is the same codec of the output...i will try some converter that can do avchd into dib then

It looks like I have lost the .mts extension from PIPP's video type list at some point. Could you try changing the filename to end in .mov instead of .mts and see if PIPP is happy with it then?  That just tricks PIPP into accepting the file.

Cheers,

Chris

[egidio]

It looks like I have lost the .mts extension from PIPP's video type list at some point. Could you try changing the filename to end in .mov instead of .mts and see if PIPP is happy with it then?  That just tricks PIPP into accepting the file.

Cheers,

Chris

Didn't work =( It's the latest pipp's release, i don't know why it doesn't accept mts!! =(

[cgarry]

Didn't work =( It's the latest pipp's release, i don't know why it doesn't accept mts!! =(

I have sent you a PM with a link to an updated version of PIPP that should handle .mts files again.  Could you try this version and let me know if it works for you?

Cheers,

Chris

[egidio]

I have sent you a PM with a link to an updated version of PIPP that should handle .mts files again.  Could you try this version and let me know if it works for you?

Cheers,

Chris

it works!!!!!!!!!! <3 thank u so much! So you work with avchd files too? what do u think about the quality? especially after the conversion in avi dib by pipp...

[cgarry]

That is great news.  Thanks for testing that version of PIPP, I will get it released in case it is causing others are having the same problem.

I don't use avchd files myself, but I know of a few guys who have used it.  Although the 'planetary imaging rules' say that using lossy video is a bad idea, I have seen some very nice results created from DSLRs using lossy videos.

I had a quick play with your video and I could not get any more detail out of it than you did.  As soon as I applied any kind of wavelets to the stacked image it just exploded with onion rings.  I am not sure why this happens but the low levels in the video (around 30%) almost certainly do not help.

Cheers,

Chris

[egidio]

That is great news.  Thanks for testing that version of PIPP, I will get it released in case it is causing others are having the same problem.

I don't use avchd files myself, but I know of a few guys who have used it.  Although the 'planetary imaging rules' say that using lossy video is a bad idea, I have seen some very nice results created from DSLRs using lossy videos.

I had a quick play with your video and I could not get any more detail out of it than you did.  As soon as I applied any kind of wavelets to the stacked image it just exploded with onion rings.  I am not sure why this happens but the low levels in the video (around 30%) almost certainly do not help.

Cheers,

Chris

Yeah I probably made a very bad video itself...gonna try again with some other settings on the camera, and do at least 3 minutes...

[egidio]

My camera has AVCHD FINE and AVCHD NORMAL...maybe the fine is lossless and the normal is lossy?

[egidio]

http://en.wikipedia.org/wiki/List_of_codecs indeed here the h.264 is under LOSSLESS, and my mts is h.264

[cgarry]

From http://en.wikipedia.org/wiki/H.264/MPEG-4_AVC:

H.264 is typically used for lossy compression in the strict mathematical sense, although the amount of loss may sometimes be imperceptible. It is also possible to create truly lossless encodings using it — e.g., to have localized lossless-coded regions within lossy-coded pictures or to support rare use cases for which the entire encoding is lossless.

Yes, H.264 can be lossless, but I have never come across this in the real world.  You capture file is certainly not lossless, it is far too small for that to be the case.

I would choose 'AVCHD FINE' as it will be better quality, though I am pretty sure it will still be lossy.

Cheers,

Chris

[egidio]

LoL, just made a test, so... 1080p avchd FINE was 38mb for 2 minutes video, i just made a 2 minutes video but choosing "normal" and it's 300MB!!! How so? Is it because maybe it uses a lossless codec?

[egidio]

I checked the info on vlc and it shows this for both: