Slice Tool (no not the one in Photoshop)

B
Posted By
Bernie
Dec 31, 2003
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765
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6
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Closed
greets all,

I’ve been trying to find a "slice tool" that can be used to display an RGB value graph from a "slice" of an image (not to be confused with the ‘Slice Tool’ in Photoshop)

It’s used a lot in compositing: basically it is just a program/application that allows you to "draw" a line (1 pixel in width) across any image. You click the mouse at the starting point, draw the line across the image, and then release the mouse at the ending point. After this, a graph will appear, showing the luminance and/or RGB values for that one-pixel-wide slice/line that you just made on the image.

It’s great for seeing if a blue/green screen is evenly lit, or showing the transition values of the FG to the BG blue/green screen, etc.

This tool is talked about in the book ‘Digital Compositing for Film and Video’ by Steve Wright. But haven’t been able to find one.

Does anyone know of an image tool that has this feature or will do this? Thanks.

MJ
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MR
Mike Russell
Dec 31, 2003
Michael J. wrote:
greets all,

I’ve been trying to find a "slice tool" that can be used to display an RGB value graph from a "slice" of an image (not to be confused with the ‘Slice Tool’ in Photoshop)

It’s used a lot in compositing: basically it is just a
program/application that allows you to "draw" a line (1 pixel in width) across any image. You click the mouse at the starting point, draw the line across the image, and then release the mouse at the ending point. After this, a graph will appear, showing the luminance and/or RGB values for that one-pixel-wide slice/line that you just made on the image.

It’s great for seeing if a blue/green screen is evenly lit, or showing the transition values of the FG to the BG blue/green screen, etc.

This tool is talked about in the book ‘Digital Compositing for Film and Video’ by Steve Wright. But haven’t been able to find one.
Does anyone know of an image tool that has this feature or will do this? Thanks.

With some effort, this can also be done using displacement maps in Photoshop.

Copy and paste a 1 pixel high selection from your image to a 1xN image, save it, and use it as a displacement map for an image N pixels wide and 256 pixels high consisting of a horizontal straight line.

For an example, download the Curvemeister profile plotter action: http://www.curvemeister.com/

—

Mike Russell
www.curvemeister.com
www.geigy.2y.net
B
Bernie
Dec 31, 2003
To help better clarify, here are some examples of how this application and process works. These are some pictures and their corresponding graphs.

http://68.54.196.116/cimage1.jpg
http://68.54.196.116/cgraph1.jpg

http://68.54.196.116/cimage2.jpg
http://68.54.196.116/cgraph2.jpg

http://68.54.196.116/cimage3.jpg
http://68.54.196.116/cgraph3.jpg
B
Bernie
Dec 31, 2003
On 31 Dec 2003 04:56:52 GMT, (MSu1049321) wrote:

in your NLE system of choice, Do a box wipe to black on a still frame you want to analyze, adjust the wipe parametersto get the ‘slice" you want, maybe export to photoshop and look at the histogram, or if on FCP or new Avid, use the scopes there.

The only problem I could foresee is that Photoshop will probably look at the pixels collectively and simply give an average for all the pixels in the slice rather than graphing them in a more linear fashion. To help clarify, have a look at the following page:

http://68.54.196.116/compos.html

Notice how the numerical graph shows the luminance/RGB values of the pixels in a linear way, the same way in which the line or "slice" was drawn. In this case, from left to right. Would this work with a histogram in PS?

MJ
MR
Mike Russell
Dec 31, 2003
Michael J. wrote:
greets all,

I’ve been trying to find a "slice tool" that can be used to display an RGB value graph from a "slice" of an image (not to be confused with the ‘Slice Tool’ in Photoshop)

It’s used a lot in compositing: basically it is just a
program/application that allows you to "draw" a line (1 pixel in width) across any image. You click the mouse at the starting point, draw the line across the image, and then release the mouse at the ending point. After this, a graph will appear, showing the luminance and/or RGB values for that one-pixel-wide slice/line that you just made on the image.

It’s great for seeing if a blue/green screen is evenly lit, or showing the transition values of the FG to the BG blue/green screen, etc.

This tool is talked about in the book ‘Digital Compositing for Film and Video’ by Steve Wright. But haven’t been able to find one.
Does anyone know of an image tool that has this feature or will do this? Thanks.

I’m intrigued by this. It seems to have some of the functionality of a histogram while keeping a tight link to image content.

I’m not familiar with Steve Wright’s work. Can you describe how you would use this functionality?
—

Mike Russell
www.curvemeister.com
www.geigy.2y.net
B
Bernie
Dec 31, 2003
On Wed, 31 Dec 2003 10:31:11 GMT, "Mike Russell" wrote:

I’m intrigued by this. It seems to have some of the functionality of a histogram while keeping a tight link to image content.

I’m not familiar with Steve Wright’s work. Can you describe how you would use this functionality?

It’s used primarily in compositing. Since compositing is largely a "mathematical" process (by hardware and software standards), it’s very useful to be able to see specific values for luminance or RGB in any given area of an image.

It is often of particular importance to be able to see the luminance/RGB value changes across a region of interest, like from the foreground person/object/talent to the blue or green screen. It’s also very handy to see just how evenly lit the screen is.

In short, when you know what the specific luminance/RGB values are, and can put numbers to them, it makes it much easier to perform gamma, luminance and color corrections, enabling you to pull a much better matte and therefore create a much more realistic and better looking composite.

Now if I could just finf this wonderful tool 🙂

MJ
H
halftone175
Jan 1, 2004
I am sure I am missing something but here goes.
How about using the marquee (rectangle) set to one pixel wide by however long you need it to be. or the single row marquee tool and then display the histogram for the selection? It is not as good as being able to click at the start and end but it shows selected histograms

Michael J. wrote:
greets all,

I’ve been trying to find a "slice tool" that can be used to display an RGB value graph from a "slice" of an image (not to be confused with the ‘Slice Tool’ in Photoshop)

It’s used a lot in compositing: basically it is just a program/application that allows you to "draw" a line (1 pixel in width) across any image. You click the mouse at the starting point, draw the line across the image, and then release the mouse at the ending point. After this, a graph will appear, showing the luminance and/or RGB values for that one-pixel-wide slice/line that you just made on the image.

It’s great for seeing if a blue/green screen is evenly lit, or showing the transition values of the FG to the BG blue/green screen, etc.
This tool is talked about in the book ‘Digital Compositing for Film and Video’ by Steve Wright. But haven’t been able to find one.
Does anyone know of an image tool that has this feature or will do this? Thanks.

MJ

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