dnheller
member
Reged: Mon
Posts: 51
Loc: Potomac, MD USA
|
|
I just noticed last night that placing the cursor over a darker mid-tone results in the green dot showing up at far left of the curve, at or near zero value on the x axis.
Straight conversion to 16-bit TIF with no curve or exposure adjustment shows an identical image on screen in another tool (I use Picture Window Pro 3.5 from http://www.dl-c.com for my tweaking outside of RSP).
When I attempt curve transformation in PWP on the 16-bit TIF, it shows histogram. The histogram probe allows me to place the cursor over the same place of darker mid-tone, resulting in the indicator (equivalent to RSP's green dot) on the curve showing properly, that is, about 1/3 of the way into the x-axis.
So it appears there is a related bug in RSP.
Michael, hope you can look into this.
Regards,
David Heller
--------------------
David Heller
|
John_Hollenberg
Resident BugBuster
Reged: Fri
Posts: 1472
Loc: California, U.S.
|
|
Previously reported, hoping for a fix in 1.02 service release.
--John
--------------------
FiveD, TenD
P4, Windows XP Home SP2
|
MichaelTapes
moderator emeritus
Reged: Thu
Posts: 6766
Loc: Florida Space Coast
|
|
......
--------------------
Michael Tapes
moderator emeritus
--
RAWWorkflow.com
WhiBal--Archive Creator--GM Color Checkers
--
mtapes@RawWorkflow.com
|
lightwriter
member
Reged: Sun
Posts: 5
Loc: California, USA
|
|
That actually sounds like a gamma curve issue.
When you apply a gamma curve to the raw data, the areas (zones) on the right-hand side (the shadows) are compressed on the X-axis (ie zone 1 is narrower than zone 2, which in turn is narrower than zone 3, etc.) resulting in a more even (linear) distribution. The image being viewed in RSP is pre-gamma curve and the image being viewed in PWP is post-gamma curve.
Does this sound right to anyone else?
I don't think it's a bug as much as a choice in the coding of the histograms graphic appearance.
C Painter
--------------------
F8 and be there! Or better yet, ADEP and get a clue.
|
John_Hollenberg
Resident BugBuster
Reged: Fri
Posts: 1472
Loc: California, U.S.
|
|
We haven't heard one way or another whether this is a bug or a feature. If a feature, some explanation and documentation would be nice. I have never been able to figure out the meaning of the Green Dot. Perhaps Michael can check with R&D and get a definitive answer for us on this.
--John
--------------------
FiveD, TenD
P4, Windows XP Home SP2
|
Goldstueck
member
Reged: Thu
Posts: 15
Loc: Germany
|
|
Quote:
I have never been able to figure out the meaning of the Green Dot.
Me too!
Please clear this question ...
|
MichaelTapes
moderator emeritus
Reged: Thu
Posts: 6766
Loc: Florida Space Coast
|
|
The green dot shows the place on the curve that the current cursor position represents, just like the small line on th bottom of the histogram. In the case of the green dot, it is showing you where to adjust the specific cursor luminosity. You can lock that place with the spot meter (Control+Click).
I do not see any remaining bug in the green dot on a quick glance. it tracks the same as the histogram line at the bottom, but offset by varying amounts because the data is still in the linear space at the place the curves adjusts the data.
Does that help?
--------------------
Michael Tapes
moderator emeritus
--
RAWWorkflow.com
WhiBal--Archive Creator--GM Color Checkers
--
mtapes@RawWorkflow.com
|
John_Hollenberg
Resident BugBuster
Reged: Fri
Posts: 1472
Loc: California, U.S.
|
|
Michael,
So you are saying that if there is no curve set on the levels/curves tab that the Green Dot and the Line on the Histogram should be the same?
--John
--------------------
FiveD, TenD
P4, Windows XP Home SP2
|
skirkpatrick
Member
Reged: Sun
Posts: 108
Loc: Israel/California
|
|
Remembering that this is in the proprietary area of algorithms for processing the raw image -- if Michael really told us what was going on, he'd have to shoot us -- I think he does mean that the green dot and the horizontal axis on the upper histogram are in the linear space. Those are the RGB numbers that you get with the left shift key pressed down. And the green dot and the horizontal axis on the lower histogram are in the "gamma-corrected" RGB space (the usual numbers shown at various places in the application). Watching the numbers both ways while I move the cursor around and see the dot move on both histograms, this seems to be the right explanation.
scott
|
MichaelTapes
moderator emeritus
Reged: Thu
Posts: 6766
Loc: Florida Space Coast
|
|
The part that Scott missed is that, NO, the dot and the line will never match up, although they will track with a varying offset.
--------------------
Michael Tapes
moderator emeritus
--
RAWWorkflow.com
WhiBal--Archive Creator--GM Color Checkers
--
mtapes@RawWorkflow.com
|
IainMackenzie
member
Reged: Sun
Posts: 296
Loc: Cornwall, UK
|
|
Unless I'm missing something here, my green dot is always on the line. No offset at all.
|
John_Hollenberg
Resident BugBuster
Reged: Fri
Posts: 1472
Loc: California, U.S.
|
|
OK, assuming I understand all of these explanations (this is a hypothetical question  ), why is the Green Dot shown still in the Linear Space? What is the purpose of doing this? How will it help us to develop better images from our RAW files? It seems that most of us find this massively confusing (I need some company here  ) rather than helpful, hence my question.
--John
--------------------
FiveD, TenD
P4, Windows XP Home SP2
|
Kyle_Nagel
Member
Reged: Thu
Posts: 1790
Loc: Utah, USA
|
|
John,
I agree, for a long time I didn't even get involved in the green dot posts because I didn't think it worked, and wasn't completely sure what it did. Even knowing now what it is supposed to do, like you, I'm not sure how I would use it to aid me in anything I'm doing. So yes, if someone can explain how this can be used then please enlighten those of us that are confused.
Kyle
PS: John, I'm seconding your question, but I'm glad you asked first!
--------------------
Pentax *istD/Tyan Thunder K7X Pro/2GB
AMD MP Dual 2400+ (2 Ghz)/Win XP Pro SP2
256mb Matrox Parhelia RT.X100/Epson R2400
Profiled/Calibrated Sony Artisan
RSP 1.0.2 Bld 77/Color Engine Build 18
|
Fred_Spencer
a member
Reged: Mon
Posts: 1017
|
|
I don't know how much this is useful but I have found the following way of using the green dot:
If you want to make a curve around a given point in your shot put the picker over that spot (the dot will track to that spot on the line), right click will then lock the green dot to that spot. The dot works as an axis point which you can lock with a left click (on the dot itself which changes its colour) - essentially you have now picked your own mid point. Once you have locked that point the dot becomes free again and you can repeat the process - e.g. find a shadow area you want to lighten and do the right click on that, move to the chart and either lock it the same or pick up the dot and move it till you are happy. You can also do the same by locking a highlight point.
I'm not sure I've explained this too well but have a go and see what you think.
--------------------
Progress has little to do with speed,
but much to do with direction
|
skirkpatrick
Member
Reged: Sun
Posts: 108
Loc: Israel/California
|
|
I agree that it is confusing to have two different RGB scales to look at. It's especially so if you try to figure out how to convert how they are related, since R, G, and B seem to scale up differently. But if you are looking at retrieving data from slightly overexposed highlights, the first histogram shows you more at the upper end of the scale. You can see about a stop higher and decide whether that looks like real data (worth shifting down with the EXP correction slider) or something that has been clipped off. Of course this is because of a tradition that histograms only show values from 1 to 256, even though our digital files may contain values that go up to 12 or even 14 bits. With logarithmic binning it would not be so hard to show the whole range -- but that is beyond a feature request.
scott
|
Previous
Index
Next
Threaded
Edit
Reply
Quote
