Strange output from DNG files, JPG are normal - page 4 - General Help and Assistance on using CHDK stable releases - CHDK Forum supplierdeeply

Strange output from DNG files, JPG are normal

  • 40 Replies
  • 10520 Views
*

Offline Pier

  • ***
  • 128
Re: Strange output from DNG files, JPG are normal
« Reply #30 on: 18 / February / 2012, 14:36:59 »
Advertisements
@Microfunguy,
Fine ! Will test that.
I'v former jasc Paint Shop Pro 10 graphic editor (now days Corel Paint Shop Pro X...), but
never used Layers in the soft.This soft work and with RAW but no recognize Canon RAW nor DNG.Anyway... thanks again for the help.
---------------------------------------
Edit - The file IMG_0052.JPG in Zip is native (without any touch) downloaded from SX130Is.
« Last Edit: 18 / February / 2012, 14:57:50 by Pier »

Re: Strange output from DNG files, JPG are normal
« Reply #31 on: 18 / February / 2012, 14:53:56 »
If you take another image set please upload them.

I am using an old PSP 9.

Quote
Edit - The file IMG_0052.JPG in Zip is native (without any tuch) downloaded from SX130Is.

Yes, but it is not 4000x3000.

*

Offline Pier

  • ***
  • 128
Re: Strange output from DNG files, JPG are normal
« Reply #32 on: 18 / February / 2012, 15:08:08 »
@Microfunguy,
Yes, Will be another set of images but little bit later - very bad weather condx  here - overcast,cold, snow, e.t.c.Not for men outside   :) - but getting to improve..
The image is not 3000x4000 because shot was made with Medium resolution 6M/ 2816/2112 pixels.
Will correct that next time.

*

Offline Lebeau

  • ***
  • 187
Re: Strange output from DNG files, JPG are normal
« Reply #33 on: 18 / February / 2012, 16:23:00 »
Here is a JPG-DNG comparaison of my SX230 (5mm focal) pictures.
Up-Left: jpg (3000x4000);
Up-Right: dng (3000x4000);
Down-Left: dng with 80% geometric deformation, scale 150% using Photoshop (3000x4000);
Down-Right: "down-left" cropped at 2478x3402;


To conclude, the jpg is generated from the raw data, performing geometric deformation and scaling up about 180%


Re: Strange output from DNG files, JPG are normal
« Reply #34 on: 18 / February / 2012, 18:40:17 »
the jpg is generated from the raw data, performing geometric deformation and scaling up about 180%

Interesting.

Do you know what mathematical function PhotoShop uses ?

Is there a focal length for which distortion in the raw is minimal ?

Presumably you get slight pincushion distortion at the telephoto end.

*

Offline Pier

  • ***
  • 128
Re: Strange output from DNG files, JPG are normal
« Reply #35 on: 19 / February / 2012, 03:03:42 »
@Microfunguy,
Quote
Do you know what mathematical function PhotoShop uses ?
Take a look at:
http://en.wikipedia.org/wiki/Distortion_(optics) - Software correction.Maybe something like that...

Re: Strange output from DNG files, JPG are normal
« Reply #36 on: 19 / February / 2012, 05:27:48 »
@Microfunguy

On my SX130IS, I zoom in to about 69mm (anything over about 60 is probably fine) if I want a DNG file with no distortion. At the top of the screen it says "25cm" as the minimum focal distance, and the aperture goes to 4.0 by this point. (for those who have not turned on the focal length display). From this point all the way to telephoto, I do not do any corrections, all photos look good to me.

I have some Photoshop settings that I use to correct shots taken at 28mm wide. However, I have not played with the focal lengths between 28mm and 69mm...  I just avoid shooting them to keep things simple.


*

Offline Lebeau

  • ***
  • 187
Re: Strange output from DNG files, JPG are normal
« Reply #37 on: 19 / February / 2012, 12:18:33 »
Like Mr_Speedy said, the geometric distortion is reduce with greather focal length.

I would underline two related aspects, the sensor field of view and the focal plane curvature.

At 05 mm focal length, the sensor field of view is about 70 deg per 4000 sensor pixels.
At 17 mm focal length, the sensor field of view is about 20 deg per 4000 sensor pixels.
At 44 mm focal length, the sensor field of view is about 05 deg per 4000 sensor pixels.

Concerning the focal plane curvature, you have to imagine that it is an arc of cricle (the focal plane) and the sensor plane is a chord or a tangent to that arc of circle. The sensor plane seams to tangent to the circle since there are few distortion at high mm and lost of focus all over the dng except at his center, and therefore, no apparent pincushion.

From the previous data, the gap between the arc and the tangent is greather with 70 deg sector than with 5 deg sector. (http://en.wikipedia.org/wiki/Circle)

Here is a comparaison between DNG and JPG. At the top, sample from the top-right corner; at the bottom, sample from the bottom-left; at the center, sample from the horizontal center. At 5 mm, after correcting barrel effect about 80% and scaling up (1.33)^2, dng leaves moustache effect.



P.S.: On the previous photo, I optimize dynamic range to increase contrast

P.S.: I red the wikipedia defs. To have a curved sensor ... http://en.wikipedia.org/wiki/Petzval_field_curvature

P.S.: for 4000x3000 sensor, diagonal is 5000 pixels and therefore, about 87,5 deg at 5 mm focal length
« Last Edit: 19 / February / 2012, 12:57:05 by Lebeau »


*

Offline fe50

  • ******
  • 3115
  • IXUS50 & 860, SX10 Star WARs-Star RAWs
    • fe50
Re: Strange output from DNG files, JPG are normal
« Reply #38 on: 03 / March / 2012, 09:28:00 »
About the purple DNG images - the origin question was:

This is how it looks like guys. Someone help!

then...
This is how it looks like guys. Someone help!
As Microfunguy said, that looks like an incorrect cfa pattern. If you tell me which Canon firmware version of A3300 you have, I can make you a test build with the other pattern.
...no related feedback  >:(

--> the same issue as with the SD1300, wrong mosaic type when converting to DNG:

As I say, I have tried both CFA patterns since then.
Use the correct mosaic type when you convert the raw, then the image is ok ;)
(DNG4PS-2 settings & DNG preview attached)

...so the discussion "RAW or not RAW" can go on ! :-X

*

Offline Lebeau

  • ***
  • 187
Re: Strange output from DNG files, JPG are normal
« Reply #39 on: 03 / March / 2012, 10:38:33 »
Concerning the purple photo, IMHO, it could be caused by CFA pattern (already tried), but also by the little/big endianneese swap.

During my tries concerning endian swap, I swap raw data to prepare dng format but didn't unswap for jpg Canon save. I got a purple jpg but a right colored DNG.

May be the swap process is not aligned with raw data ?

 

Related Topics