What exactly is midtone

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norris_watkins
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Scanner: Epson V700
SilverFast Product: SE Plus

What exactly is midtone

Postby norris_watkins » Mon Nov 21, 2011 4:40 am

These questions are w.r.t Silverfast SE Plus 8.0
Silverfast documentation movie says it is the 'overall brightness'
1. But how exactly is the midtone calculated.
Is it teh average brightness of the pixel ? ( Or is it teh mean brightness ? )
2. Also how is it calculated in the 'L' ( Logirithmic ) mode ?
( When I looked at the Gradation curve, I see that it changes differently depending on whether you select 'L' ( Logarithmic ) or 'N' ( Normal ). - so the calculation has to be different )
3. Also I see that in the histogram window, midtone value shown on the graph is different from teh midtone value shown numerically as shown in the picture. Why is this ?
4. Is there a way to see the input historgram in SF ?
( I see the histogram getting affacted when I make various changes - So it has to be the output histogram )

LSI_Morales
SilverFast Master
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Joined: Mon Oct 22, 2007 9:33 am

Re: What exactly is midtone

Postby LSI_Morales » Thu Nov 24, 2011 3:39 pm

Hi norris,

The midtone is the point located in the middle between the brightest and the darkest point in your picture's histogram. If you move the midpoint it will affect the overall brightness.

norris_watkins wrote:Also how is it calculated in the 'L' ( Logirithmic ) mode ?
( When I looked at the Gradation curve, I see that it changes differently depending on whether you select 'L' ( Logarithmic ) or 'N' ( Normal ). - so the calculation has to be different )


The midpoint does not change between Logarithmic or normal views.

norris_watkins wrote:3. Also I see that in the histogram window, midtone value shown on the graph is different from teh midtone value shown numerically as shown in the picture. Why is this ?


I'm afraid I don't really get this question, would you please elaborate?

norris_watkins wrote:4. Is there a way to see the input historgram in SF ?
( I see the histogram getting affacted when I make various changes - So it has to be the output histogram )


Sure, the input histogram is the one you see in the "Histogram" tool, the output histogram is the one you see in the "Picture settings" panel

Cheers
Alejandro Morales

LaserSoft Imaging
Media manager, Software testing

norris_watkins
SilverFast Beginner
Posts: 20
Joined: Mon Nov 07, 2011 8:16 pm
Scanner: Epson V700
SilverFast Product: SE Plus

Re: What exactly is midtone

Postby norris_watkins » Tue Jan 24, 2012 10:55 pm

Thank you Morales. Few questions still remain :

The midtone is the point located in the middle between the brightest and the darkest point in your picture's histogram. If you move the midpoint it will affect the overall brightness.

1. Im not sure this is true. Im looking at the histogram now ( shadow=83, midtone=-9, highlight=254). If its the midpoint between brighttest and darkest points, then it should have been 168.5 ( 83+254)/2 = 168.5

2. What does it mean to change midtone to 'Logarithmic' ( by clicking the rectangle 'L' next to 'Midtone' in 'Picture Settings' )

3.
Sure, the input histogram is the one you see in the "Histogram" tool, the output histogram is the one you see in the "Picture settings" panel

But I dont have any histogram in 'Picture Settings'

LSI_Morales
SilverFast Master
SilverFast Master
Posts: 1430
Joined: Mon Oct 22, 2007 9:33 am

Re: What exactly is midtone

Postby LSI_Morales » Wed Jan 25, 2012 11:18 am

Hi norris

First I will start by making a correction in my previous statement. I confused your previous question about the midtone with something else (sorry about that).

The midtone is a curve comprising the entire range of tones from the darkest point to the lightest point (without changing darkest and lightest points). These can be seen by opening the gradation curve and moving the midtone slider (either in gradation curves panel or in the picture settings pannel) or by moving the midtone slider in the histogram.

norris_watkins wrote:1. Im not sure this is true. Im looking at the histogram now ( shadow=83, midtone=-9, highlight=254). If its the midpoint between brighttest and darkest points, then it should have been 168.5 ( 83+254)/2 = 168.5


The scale of the midtone is independent from the rgb values of the histogram (0-255); it extends from -30 to +30 where 0 represents a straight line and -30 and + 30 the extremes (you can see this by moving this value while looking at the curve).

norris_watkins wrote:2. What does it mean to change midtone to 'Logarithmic' ( by clicking the rectangle 'L' next to 'Midtone' in 'Picture Settings' )


It changes from a normal curve to a logarithmic curve (again check the gradation curve to see the difference, most apparent at both extremes).

norris_watkins wrote:But I dont have any histogram in 'Picture Settings'


The output histogram is available only in SilverFast Ai Studio, it is part of the picture settings panel and looks like this:
Output Histogram.png
Output Histogram.png (20.82 KiB) Viewed 2054 times


Kind regards
Alejandro Morales

LaserSoft Imaging
Media manager, Software testing


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