NON Square Cropped Portraits - (nSCP's) - Archive

[Dave Humphries]

But here is my question: if this is raw data from the sensor, where does that 20% go and what does it carry that is so useless?

I'm (slightly educated) guessing here, but I suspect that it is "losslessly compressed", so rather than be just a bitmap of the bayer array, it looks through the pixels line by line for ones with identical values and, in my 5 pixel example; rather than sending 216, 222, 222, 222, 234 it sends 216, 3 x 222, 234 ...

So the % amount of saving is likely to be image content related, shots of finely detailed forests are likely to give less saving than say, one of Fernando's images with large areas containing the same tone.

However, unlike jpg compression, the image can be faithfully reconstructed in it's entirety.

What I describe is called Run Length encoding, don't go further than their Example, or your head may hurt.

Cheers,

[carregwen]

Thanks, Rob. I love the way you bring out all the natural colors and ...

Oops! I forgot that. I added some vibrancy slider in the RAW to tweak the colour a bit. Vibrancy is more subtle than the saturation slider. Like me - subtle. So don't forget that if you try it.

[carregwen]

Once I did this and the DNG file came out at 40MB or so. I think I may have included the RAW file (used that option) but anyway that was my impression always that it increases the size.

I think I can just convert to DNG only and reduce size.

But here is my question: if this is raw data from the sensor, where does that 20% go and what does it carry that is so useless?

The data is still there. It uses run length coding as Dave said. It's all zeros and ones, f you get a string of say 10 ones you just set one and indicate how many, then you don't need to record them all, hence the space saving. Something like that - it's a long time since I was a software engineer.

If you end up with 5,000 RAW files (you might) that would mean an extra 4G of disk space AND it will take longer to back up/restore. The bigger the camera file (like 5D) the worse it gets.

[Antonio Correia]

Ali When I downloaded your file it was 23.5MB. I converted to DNG with Adobe converter and it reduced to 19MB - a saving of 20%. Those 5D files are big, do you convert them to save disk space?

The downloaded file is 24.6 MB in my computer.

Rob, I see no other advantage than a bit more of hard disk space to convert RAW into DNG apart the embedded XMP data. Why do you do that ? Don't you think that RAW files will be as long as DNG ones in terms of life spam ?
EDIT-I read about this in this very thread. Thank you. I am keeping my RAW files in spite of.

Alis,
Carefully examinating the file opened in LR and zoomed, I saw that it is not focused correctly on your young man's face but on his left pocket

But these are the dangers of shooting wide open aren't they ?
Anyway I think that the second photo you posted is far more interesting because he has a better face expression as you said yourself and you didn't cut his leg.

Thank you for posting once again
I hope to be able to always give my feed back.

[carregwen]

The downloaded file is 24.6 MB in my computer.

Rob, I see no other advantage than a bit more of hard disk space to convert RAW into DNG apart the embedded XMP data. Why do you do that ? Don't you think that RAW files will be as long as DNG ones in terms of life spam ?

DNG is Adobe's 'open standard' so I guess they will be around for a long time. But who can tell. It does also get around the problem of having to upgrade Photoshop to get the latest RAW-ACR version if you buy a new camera model. And finally, because I am a control freak and I can't sleep at night knowing there's an extra 3GB on my drive!

Alis,

Carefully examinating the file opened in LR and zoomed, I saw that it is not focused correctly on your young man's face but on his left pocket

I noticed that. Probably because his left shoulder was the closest thing to the lens on autofocus.

[Antonio Correia]

... I saw that it is not focused correctly on your young man's face but on his left pocket...

...I noticed that. Probably because his left shoulder was the closest thing to the lens on autofocus.

Alis my friend I have to tell you; this photo would be discarded if it was mine. Sorry.
It also does happen to me ... which makes me very mad and makes me think that I am moving the camera at the same time I am moving the right finger but it is not so.
You are not mad at me, are you ? Course not

[Ashwin]

Thanks, Ashwin. The one on the left looks a llittle bit washed out but between the other two I don't see that much difference at this size but they both look nice!

Hi Ali,

1st picture, that is on extreme left side is your Raw File as the link provided by you, I have not done anything on this, 2nd ( Middle ) image I have corrected and little sharpness added in the left side hand, and in the 3rd image extremely right side, I have blurred the tree

2nd image is posted again

[peterb533]

[Antonio Correia]

Oh is he looking at the scones ?
That light from the background gives him a special touch...

[peterb533]

Oh is he looking at the scones ?
That light from the background gives him a special touch...

The back ground light caused a problem with the colour balance, hope I got it correct.

He had actually just seen his Mum come back into the room with his supper

[peterb533]

Our beautiful grandaughter Abigail having a great time at Easter. Might not be the best technically but I love the expression on her face.

[Alis]

Hi Ali,

1st picture, that is on extreme left side is your Raw File as the link provided by you, I have not done anything on this, 2nd ( Middle ) image I have corrected and little sharpness added in the left side hand, and in the 3rd image extremely right side, I have blurred the tree

2nd image is posted again

Thanks, Ashwin. I am not sure if this is the best way to process this, since it looks too dark overall. But it is a more serious version of the image. Thanks!

[Alis]

Alis my friend I have to tell you; this photo would be discarded if it was mine. Sorry.
It also does happen to me ... which makes me very mad and makes me think that I am moving the camera at the same time I am moving the right finger but it is not so.
You are not mad at me, are you ? Course not

I am really mad at you, Antonio! How dare you? I do not discard my images, that is why I keep buying hard drives, one terabyte after another...

But you are right. It is not good enough for large print, and that was a good catch. You really pay attention to details. I have to learn that.

I have more of these pictures, I can look at rest of them and find a better one, like the one I posted after this one. I basically put him up on that tree and he immediately started looking for a way to come down. It was not a tall tree, so he jumped down in less than a minute, and that is why I just too whatever I could, but I took a lot of them. I am still waiting for the right age, when he can actually pose for me

Thanks for the comments!

[Alis]

I'm (slightly educated) guessing here, but I suspect that it is "losslessly compressed", so rather than be just a bitmap of the bayer array, it looks through the pixels line by line for ones with identical values and, in my 5 pixel example; rather than sending 216, 222, 222, 222, 234 it sends 216, 3 x 222, 234 ...

So the % amount of saving is likely to be image content related, shots of finely detailed forests are likely to give less saving than say, one of Fernando's images with large areas containing the same tone.

However, unlike jpg compression, the image can be faithfully reconstructed in it's entirety.

What I describe is called Run Length encoding, don't go further than their Example, or your head may hurt.

Cheers,

Thanks, Dave and Rob. I am guessing RAW format does not use the same compression algorithm when saving RAW files because it is a burden on the camera's processor?

[Dave Humphries]

Thanks, Dave and Rob. I am guessing RAW format does not use the same compression algorithm when saving RAW files because it is a burden on the camera's processor?

Quite possibly.

I vaguely remember a thread talking of something called sRAW a while back. I got the impression that may have done this, it was a settable option, presumably so for a quicker frame rate you just used uncompressed RAW instead.

Cheers,

[Colin Southern]

@ Dave & Ali

RAWs are always compressed - but (of course, and as you mentioned Dave) losslessly - so the file size comes down to how "squishy" the data is. Out of interest, high-ISO files are bigger due to the noise. As far as I know sRAW aren't processed any differently, but I did notice a bit of an anomaly with their size just a few days ago, do I'll need to investigate some more. The main advantage of sRAW is just to allow you to get more images on a card @ lower resolution, but whilst still retaining all the other benefits of a RAW capture.

[flipmode]

Thanks you Antonio. Sorry for the late reply back.

[Dave Humphries]

RAWs are always compressed - but (of course, and as you mentioned Dave) losslessly - ~

The main advantage of sRAW is just to allow you to get more images on a card @ lower resolution, but whilst still retaining all the other benefits of a RAW capture.

Yes, of course - now you mention it, that explains why a fixed bayer pattern, which should, if uncompressed always produce the same size file, actually results in different RAW file sizes (from 9.4 to 11.7MB in my recent downloads)

So sRAW does what, crops the edges off?

Sorry Antonio, we might hack this bit out if it goes on too long.

[Colin Southern]

So sRAW does what, crops the edges off?

It lowers the effective resolution, but how they do it -- they ain't saying! The buzz was that they might be pixel binning (effectively averaging with adjacent pixels to create a psudo-larger photosite resulting in lower noise, but off memory when Sean posted some examples a while back it didn't seem to support it - so possibly they're just discarding a certain % of the information).

I don't normally use it, but was experimenting with it the other day shooting tethered to my 40" TV ... problem I have is that it takes about 7 seconds for a full RAW file to transfer and display - but if I capture full RAW to one card and sRAW to another - and then just send the sRAW to the TV then in theory I should get all the benefits of a RAW capture (ie no changes due to JPEG processing), but an increased transfer time (sRAW STILL has higher resolution than the TV!) - but all this got "lost in translation" whilst I was trying to figure out another problem: basically only lightroom updates the images on the screen so that you always see the laxt "X" number shot - but there's a know issue with LR3 when shooting tethered from a Canon 1Ds3 in that if you overload the buffer then it locks everything up ... and if you use the Canon EOS utility to dump the images to a specified folder and then have LR watch that folder then it doesn't lockup -- but it doesn't scroll the screen to the latest images either ... so I'm between a rock and a hard place at the moment until LR3 goes RTM.

[Alis]

I am enjoying this conversation very much! Thought I let you guys know