Luminosity Masks 8 bit?

Are the selections via Kuyper Luminosity Masks 8 bit in a 16 bit space? 
I believe it was Jeff Schewe who told me any live selection in Photoshop ("marching ants") once you make an adjustment to them, become 8 bits, even in a 16 bit space.  I asked the question years ago because I was finding very real posterization in my 16 bit processed enlargements. As soon as I weaned off the masks, the posterization discontinued...
Thank you in advance.

So what do folks say about this:
"Last year I started to receive email questions about whether luminosity selections change the bit depth of selected pixels from 16-bit to 8-bit. The answer to this is “No.” It would take something like the Image > Mode command to do that. A little research, though, showed where this misconception was coming from. It turns out that regardless of the bit depth of the image, selections are always 8-bit. Even on a 16-bit image, selections are still 8-bit. The bit-depth of the selection, though, is only referring to the degree of selection possible within the selection (up to 256 for 8-bit). The bit-depth of the image, on the other hand, is describing the amount of color information each pixel can display (65,536 levels for each color channel in RGB). They’re not the same thing. The 8-bit degree of selection is only determining how adjustments get passed to the pixels below. It is not changing the 16-bit precision of the color data in those pixels."
I have tried a few time to reach Jeff Schewe on the mater...

Similar Messages

  • Luminosity mask

    I have PSE3 for Win Xp.
    I also have CS in which I have tried this techique for coping with large differences between the exposure values in an image.
    This relies on a Luminosity mask.
    Can I get this mask in PSE3, I cannot see how, or simultate the techique?

    A luminosity mask is just a grayscale version of the layer itself loaded as a selection. Photoshop has a simple key combination to load the luminosity mask. Elements does not. You can, however, get the luminosity mask in Elements with just a bit more work.
    If your layers palette isn't open, open it so you can see what you're doing. Begin by making the layer whose luminosity mask you want to load active. Let's call this the "base" layer to make the discussion easier to follow.
    Create a levels adjustment layer. Don't make any changes to the levels, just click ok. This will create a levels layer immediately above the "base" layer containing a layer mask. Click on the "base" layer in the layers palette to make it the active layer again and then press ctrl-A to select the entire image and then ctrl-C to copy the image.
    Now press and hold the alt key and click on the small white rectangle in the levels adjustment layer in the palette. The image should turn white as you're now editing the mask. Press ctrl-V to paste the image into the mask (you'll get a grayscale image). Press alt and click on the mask rectangle again to end editing the mask.
    Finally, press and hold the ctrl key and click on the levels adjustment layer (PSE4 will need to click on the mask thumbnail) -- This will load the luminosity mask. Leave the selection active.
    You're done with the adjustment layer, you can delete it if desired. But, if you keep it, you can reload the luminosity mask later if need be. You also have the option of saving the selection. Your choice.
    Since you have Photoshop CS, you can easily create an action for Elements to do this and execute it from the effects palette. You'll need to create the action and a thumbnail image. For instructions see http://www.cavesofice.org/~grant/Challenge/Tools/Create.html When recording the action, you can use the standard key combination to load the luminosity mask and it will work when executing the action in Elements later -- you'll have a one step action.
    The action and thumbnail will need to be placed in an appropriate PSE directory. See http://www.cavesofice.org/~grant/Challenge/Tools/HowtTo.html for a description of how to install Grant's tools. You would do basically the same thing for yours. You don't need a separate directory for each tool, if you have Grant's tools, for example, you can install yours in the same directory.
    Barbara Brundage had a good explanation for how to create your own actions for Elements also but I've misplaced the URL.
    Bob

  • [svn:fx-trunk] 11641: A simple fix - we need to keep track of the display list index for non-clipping masks such as luminosity masks , not just alpha masks.

    Revision: 11641
    Author:   [email protected]
    Date:     2009-11-10 18:29:57 -0800 (Tue, 10 Nov 2009)
    Log Message:
    A simple fix - we need to keep track of the display list index for non-clipping masks such as luminosity masks, not just alpha masks.
    QE notes: Please include tests for multiple graphic content nodes with masks under a .
    Doc notes: N/A
    Bugs:
    SDK-24133 - Multiple non-Group maskees don't work when using maskType="luminosity"
    Reviewer: Deepa
    Tests run: Checkintests, Bug test case
    Is noteworthy for integration: No
    Ticket Links:
        http://bugs.adobe.com/jira/browse/SDK-24133
    Modified Paths:
        flex/sdk/trunk/modules/compiler/src/java/flex2/compiler/fxg/FlexFXG2SWFTranscoder.java

    Revision: 11641
    Author:   [email protected]
    Date:     2009-11-10 18:29:57 -0800 (Tue, 10 Nov 2009)
    Log Message:
    A simple fix - we need to keep track of the display list index for non-clipping masks such as luminosity masks, not just alpha masks.
    QE notes: Please include tests for multiple graphic content nodes with masks under a .
    Doc notes: N/A
    Bugs:
    SDK-24133 - Multiple non-Group maskees don't work when using maskType="luminosity"
    Reviewer: Deepa
    Tests run: Checkintests, Bug test case
    Is noteworthy for integration: No
    Ticket Links:
        http://bugs.adobe.com/jira/browse/SDK-24133
    Modified Paths:
        flex/sdk/trunk/modules/compiler/src/java/flex2/compiler/fxg/FlexFXG2SWFTranscoder.java

  • [svn:fx-trunk] 11627: Fix setting luminosity masks on graphic elements - missed an occurence where setting cacheAsBitmap to true was needed .

    Revision: 11627
    Author:   [email protected]
    Date:     2009-11-10 14:01:01 -0800 (Tue, 10 Nov 2009)
    Log Message:
    Fix setting luminosity masks on graphic elements - missed an occurence where setting cacheAsBitmap to true was needed.
    QE notes: Regress
    Doc notes: No
    Bugs: http://bugs.adobe.com/jira/browse/SDK-24089
    Reviewer: Pete
    Tests run: All FXG (static and runtime) tests
    Is noteworthy for integration: No
    Ticket Links:
        http://bugs.adobe.com/jira/browse/SDK-24089
    Modified Paths:
        flex/sdk/trunk/frameworks/projects/spark/src/spark/primitives/supportClasses/GraphicEleme nt.as

    FYI - This regression has been filed here: http://bugs.adobe.com/jira/browse/SDK-31989

  • [svn:fx-trunk] 11727: You can' t just assume the first shader filter in a maskee object' s filter array is the luminosity shader when rendering a luminosity mask.

    Revision: 11727
    Author:   [email protected]
    Date:     2009-11-12 12:58:37 -0800 (Thu, 12 Nov 2009)
    Log Message:
    You can't just assume the first shader filter in a maskee object's filter array is the luminosity shader when rendering a luminosity mask. Instead, we now loop through all the filters in the array and search for the luminosity shader.
    QE notes: None
    Doc notes: None
    Bugs: SDK-24180
    Reviewer: Ryan
    Tests run: FXG runtime, FXG static
    Is noteworthy for integration: No
    Ticket Links:
        http://bugs.adobe.com/jira/browse/SDK-24180
    Modified Paths:
        flex/sdk/trunk/frameworks/projects/spark/src/spark/components/supportClasses/GroupBase.as
        flex/sdk/trunk/frameworks/projects/spark/src/spark/primitives/supportClasses/GraphicEleme nt.as

    Remember that Arch Arm is a different distribution, but we try to bend the rules and provide limited support for them.  This may or may not be unique to Arch Arm, so you might try asking on their forums as well.

  • How to create a non-destructive luminosity/b&w mask for (de)saturation?

    Someone asked me this question: CG renders (created in Modo, Max, Blender, Maya, Vray, Octane, etc) can be made to look more realistic by desaturating the colours in the highlights. It was also requested that this move would be done in 32bpc as well (something that is often required in a CG compositing workflow).
    This is easy enough to do: create a selection based on luminosity (or a black and white version of the image), and use that as a layer mask in the Hue/Saturation adjustment layer, and turn down the saturation.
    However, this is a destructive action: suppose we want to import an external file as a smart object, and then we need the option to have the file automatically update with any change we make to the original artwork.
    In that case we would have to recreate that luminosity mask again and again as well.
    Ideally, an update of the external file will result in an automatic update of the entire layer stack.
    Now, in Photoline this is easy to do:
    Since layer masks behave like regular layers in PL, and layers can be virtually cloned (not unlike smart objects), it is a mere case of cloning the original external file layer twice, and adding adjustment layers. Finally, that one instanced layer is used as a layer mask for the adjustment layer that controls the saturation. Done.
    Replacing or editing the original source will then automatically update and cascade the changes through the entire layer stack.
    This is a very handy technique to have! Since I teach Photoshop classes, I thought this would also be handy to know how to do in Photoshop, and I tried several methods (clipping masks included), but I cannot seem to achieve the same non-destructive result. Clipping masks do not work with adjustment layers. Groups cannot be used as clipping masks. Layer masks cannot reference a smart object.
    I have a feeling there ought to be a reasonably straightforward method to achieve this, but how?
    Would anyone have a suggestion how to solve this in Photoshop in a non-destructive way?

    csuebele wrote:
    I'm still not seeing it. Your example does not have a pixel based layer clipped to the group which is causing my problem. I hope I can explain this. See below. the layers in the group create the "mask". In this case a b&w adjustment layer was added to control how the "mask" is converted to b&w. You can see what these layers look like in the mid section top section of the image. any color showing though is from the very bottom layer, as the group has a blend if on it allowing the shadows to come through. The top image has a curve layer with no adjustment, while the bottom image has a curve layer to clip more of the shadows. You can see this change in the upper right corner of both images. The curves are allowing more of the image to be clipped in the area is masked out on layer "Layer 0 copy 1", as more of the color of the base layer is showing though. However, that b&w areas are suppose to be just the mask and you should see the b&w, just color as seen in the bottom image. However, the curves are not changing the transparency in the areas that have the layer to return the color.
    I don’t get it – what good is the pixel Layer ("Layer 0 copy 2") clipped to the Group supposed to do? Don’t you want to use the Mask on an Adjustment?
    Edit: Maybe this can help clarify how I suppose the issue would be approached.

  • Luminosity color mask, can i do it?

    Hi
    can i do a color luminosity mask ?
    for example for a range of colors or for yellow?
    may somebody help me?
    thanks

    Reynolds (Mark) wrote:
    mantalightroom - Color range actually makes selections based on both color AND luminosity.
    a luminosity mask based on a range of colors
    … doesn't really make sense. 'Luminosity' means tone, depth, lightness. 'Color' in its purest form, really means hue - take a hue/sat layer and shift the hue slider to see what this means.
    I agree with Mark that the OP's posts do not make sense. If the OP would indicate what he is trying to accomplish, then someone might be able to help him.

  • "Live Selections" 8 bit?

    I am having trouble getting a full response here on the Adobe Forums.  I have emailed Jeff Schewe on the issue but have not gotten anything back as of yet.
    Years ago I was getting posterization in my 16 bit enlargements and asked Jeff and others here why that might be. The question given to me was "are you using any 'live selections" in your masking? Then I was told that "live selections are always 8 bit" even in a 16 bit space.  I immediately discontinued my various "live selection" masking techniques and the posterization went away for good (I make gallery enlargements full time). I have been educating people about this for 6-7 years now. I use the Layer Style "Blend if", or I create custom 16 bit masks via Calculations now.
    But some controversy has been brewing lately about the use of Kuyper Luminosity Masks.
    Here is his quote:
    "Last year I started to receive email questions about whether luminosity selections change the bit depth of selected pixels from 16-bit to 8-bit. The answer to this is “No.” It would take something like the Image > Mode command to do that. A little research, though, showed where this misconception was coming from. It turns out that regardless of the bit depth of the image, selections are always 8-bit. Even on a 16-bit image, selections are still 8-bit. The bit-depth of the selection, though, is only referring to the degree of selection possible within the selection (up to 256 for 8-bit). The bit-depth of the image, on the other hand, is describing the amount of color information each pixel can display (65,536 levels for each color channel in RGB). They’re not the same thing. The 8-bit degree of selection is only determining how adjustments get passed to the pixels below. It is not changing the 16-bit precision of the color data in those pixels."
    It sounds to me as if he is saying that the selections in his masks are not actually 8 bit, or rendered down to 256 levels.
    Please help me get to the bottom of this issue.
    Thank you very much in advance.
    A link to his explanation is here for those who might be interested:How to Make 16-bit Luminosity Masks | Good Light Journal

    Jeff Schewe said:
    "if the selection started by having a dancing ants selection before saving as a channel or a layer mask, then they are 8 bit to start and they won't magically become 16 bit. Channels & layer masks are 16 bit in 16 bit documents, selections are always 8 bit.  I just read Tony's tutorials and yes, his masks start life as a selection that is saved to a channel (or mask) so the resulting channels saved from the selection are 16 bit but the original selection is still 8 bit. BTW, Color Range also returns an 8 bit selection"...
    So is this statement by Tony false?:
    “Last year I started to receive email questions about whether luminosity selections change the bit depth of selected pixels from 16-bit to 8-bit. The answer to this is “No.”
    Secondly, I thought I was told by someone here years ago that with PS Color Range, as long as you create the mask FIRST then the way it does its thing is different and not via live selections (and 16 bit)... Is that true?
    I cant tell you how thankful I have been to be on this forum over the years. Amazing access to the details!

  • Tips for lightening areas of a photo without masks

    Hi guys, In the exmaple below there is an image that lightens areas in contrast to others. I know set up allowed for much of this to be performed before post processing, but the blends are really nice along with the hair.
    I've tried using a luminosity mask for certain areas by using the channel mixer and then adjusting the blend if sliders. For any process I try I always end up using a lot of masks to control the adjusted areas.
    Any tips for achieving this without the harshness of masks? Painting on masks or using the adobe mask edge dectection does not leave me with a realistic results.
    Thanks so much!

    Personally, I'm very fond of the Dodge Tool.
    I suggest you work at 16 bits/channel so you don't accumulate pixel error.
    It takes a while to get to know the tool, e.g., how it responds to different image tones with Shadows, Midtones, or Highlights set.  And don't try to reach your goal all in one stroke.  Set the Exposure to a fairly low value and build up the effect with multiple strokes.
    -Noel

  • How do I process serial port strings as bits

    In response to my commands, my instrument is sending bytes to my serial
    port. In one instance, 2 bytes are received. I want to treat these 2 bytes
    as a group of 16 bits.
    The VISA and Compatibility Serial functions return these bytes from the
    serial port to Labview clearly labelled a "string".
    Everything I can find in the way of Labview functions and .vis don't want to
    do bit twiddling, bit swapping, and bit dropping, with "string" data.
    I thought "hex string to number" could be used here, but I can't find a way.
    The 2 Bytes in question can be represented as hex, but the data are not the
    ASCII codes for the hex representation of a binary number, they are the
    binary number. This "hex string to number" seems to want ASCII c
    odes.
    You can feed a hex number typed into a "control" box wired into "hex string
    to number" and you get a meaningful number. You can feed the 2 bytes from
    the serial port into an "indicator" set to read in hex and you get a hex
    number that is a correct representation. But that is Labview handing them
    around to itself. I need to get my "hands" on them.
    I can't feed those same bytes that show up as a correct hex representation
    in an indicator into the "hex string to number" or anything else, so far,
    and get a number that is useful for further processing.
    I thought "variant to data", but I can't find enough reference material to
    understand how to use it. A boolean array seems like a bit of a weird
    approach, so I thought I'd ask before I looked into that.
    I'm used to dealing directly with binary numbers on the processor stack, I
    call them whatever I want, and turn them into anything I feel like.
    I'm sure I'm staring the solution in the face, but I can't find any way to
    persuade
    Labview to treat this "string" data as 16 bits.
    I've got the 16 bits, which is better than not having them, but I don't have
    much hair left.

    duh, well I finally discovered the "Unflatten from String" function. A guy
    just feeds in the bytes he's collected from his serial port that Labview
    thinks are a "string", and out come lovely little unsigned 16 bit numbers,
    or whatever other type of number he wants to turn the bytes into. And there
    are great little bit twiddlers available after that, like "swap bytes", and
    you can mask out bits with the logic operators, why this is fun. There's
    nothing like being a moron...... fly me to the moon...................
    "David Lewis" wrote in message
    news:[email protected]..
    > The two bytes would come from a serial port read.vi in Labview, classed as
    a
    > string. For instance, D3 and 02. The output wou
    ld swap the two bytes,
    i.e.
    > to 02 and D3, consider the two swapped bytes as 16 bits, drop the six most
    > significant bits, and output the ten bits that are left as an integer
    > classed by Labview as some kind of number, not a string.
    >
    > Your example StringToBits_Converter.vi I found on the ni.com site
    > unfortunately gives an error message and refuses to open on my system
    saying
    > it comes from a newer version of Labview 6 than I am running. Mine says
    > 6.0.1b3. Thank you very much anyway.
    >
    > "FightOnSCTrojan" wrote in message
    > news:[email protected]..
    > > In another words, you want to create a VI in which the input is 2
    > > strings (i.e. AB) and the output is the converted array bits (e.g.
    > > 1010101010101010)?
    >
    >

  • How can I set specific bits in a 16-bit integer?

    Hello everyone,
    as the title says I need to modify or rather to set a specific bit in a string which then is sent to a motor. I need to be sure that my command is correct as I am experiencing troubles with that motor and need to identify if its source.
    First of all my strings have to be in the Little Endian order. Then the structure of the string should be the following:
    Change Velocity command ‘V’xxCR 056h + one unsigned short (16-bit) integer + 0Dh (Note: Uppercase ‘V’)
    Note: The lower 15 bits (Bit 14 through 0) contain the velocity value. The high-order bit (Bit 15) is used to indicate the microstep-to-step resolution: 0 = 10, 1 = 50 uSteps/step.
    Until now, I used Flatten To String to convert 32 bit integers into bytes of the correct order. I thought I could use the Join Numbers function, but that only works for at least 8 bit numbers and there is no "1 bit number". I searched for an option to build a a string and set the bits via a Boolean Cluster, but I did not really understand how to transfer this to my problem.
    How can I build up the correct 16-bit integer (e.g. set the velocity to "10000" with a resolution of 50 µSteps/step)
    I would like to add the "V" and the CR via Concatenate Strings to the 16-bit integer, but other possibilites are also welcome.
    I have seens the examples for bit manipulation in C-code, but I wish to do this with LabView as I am not familiar with C,matlab and so on.
    Thank you very much for your help!
    Solved!
    Go to Solution.

    You really need to learn Boolean logic and how to shift bits around.
    AND is really good for masking out bits (forcing them to 0) and OR is really good for adding bit values.  Then Logical Shift is used to get the bits in the right places before doing the AND and OR.
    NOTE: Rate is an enum with 10 being a value of 0 and 50 being 1.
    There are only two ways to tell somebody thanks: Kudos and Marked Solutions
    Unofficial Forum Rules and Guidelines
    Attachments:
    Bit Packing.png ‏15 KB

  • Layer Mask blur question

    I hope that I can present this question clearly. I process 2 images from a single RAW, a light and a dark layer, the dark on top. I create a luminosity mask from the light image, and then from that selection I create a Layer Mask on the dark image.
    1) Why does the resulting composite have strange colors, like a bad Curve (where it goes up to the right, and then goes down before continuing back up to the right)?
    2) Why is there marked improvement with a Gaussian Blur of 40 to the mask?
    3) When I paint on the mask in mid-gray, that section similarly improves (that would be the same as 2, ie, a homogeneous gray like a blur, but focal in this case with the brush).
    What does the Blur actually do to improve the blending? I'm sure it has to do with how the pixels are blending without the blur, but I cannot seem to understand what's going on.
    The images are in perfect registration.
    Thanks very much,
    Sonny

    I figured it out. Thanks
    Sonny

  • Creating Saturation Channel / Mask

    Hello.
    I'm interested in making a Saturation Mask. Actually I want to extract the Saturation Channel.
    I know there's HSL / HSB Plug-In made by Adobe which is able to do so.
    Yet, I'm interested if there's an option creating it using the Blend Modes (Just like adding a Solid Black Layer in Color Mode creates a Luminosity Mask).
    Could anyone assist?
    Thanks.

    This thread has revealed that not all methods out there which allegedly produce a SATURATION mask are valid.
    That seems true for LUMINOSITY masks as well, and I'd like to adress that.
    In the same way that a saturation mask was defined, let's define a luminosity mask as having gray values which everywhere correspond to the underlying luminosity. Since the  0-255 luminosity range is the same as the gray value range, correspondence in this case is equality (the 2.55 saturation multiplier is not needed).
    Luminosity in PS is  0.3R + 0.59G + 0.11B. Just for example, masking a pure, fully bright red (255/0/0) would give a gray value of 0.3 x 255 = 76. Likewise masking a pure, fully bright green (0/255/0) gives 150, and pure, fully bright blue (0/0/255) gives 28.
    The method for creating a luminosity mask cited by Royi Avital in his original post (overlaying a black layer in color blend mode) is valid in that it meets the foregoing definition of a luminosity mask and, in fact, can be expanded to overlaying any shade of gray from black to white in any of three blend modes, specifically hue, saturation, or color blend modes (note that the luminosity mode is excluded).
    There is another commonly-advocated method for producing a luminosity mask: ALT-CTRL + tilde (~). For the life of me, I cannot get it to produce grays that equal the luminosity. Since this seems to be the widely-adopted method, any challenge must indeed be hesitant. Can somebody out there substantiate or disprove my result. Why doesn't this accepted method conform to a reasonable definition of a luminosity mask? 

  • Blurring layer mask question

    I have been trying to figure out for a long time what is going on here, and am stumped.
    I have a dark and light layer from the same RAW image. The dark layer is on top.
    I create a luminosity mask (Cmd-Opt-click RGB channel) from the light image.
    I apply the selection as a layer mask to the top, dark layer.
    The detail is bad, looking, maybe, posterized. The image does have lots of fine detail.
    When I blur the layer mask, about 40, the image looks great.
    ****What does the blurring of the layer mask do, to bring out the detail of the image?**** I use layer masks often, and don't usually have to blur to see detail.
    I tried to attach/insert a small crop with the 2 layers and mask for you to see, under 2 mb, but the content is not allowed. Hopefully my description will make it easy for you experts.
    Thanks for any possble help,
    Sonny

    Hopefully this will work. Here is the link to the file, including the 2 layers, and layer mask, cropped.
    https://dl.dropbox.com/u/1660216/maskBlur.psd
    To summarize, why is it necessary to blur the layer mask ( ~40) in order to see detail?
    The mask is a luminosity mask (Cmd-Opt-click RGB channel) created from the light layer, and then applied to the dark layer.
    As I mentioned originally, I use layer masks often, and don't have to blur the mask, unless I want a special effect. It seems that whenever I blend this way, with a luminosity mask, the mask has to be blurred.
    Correction from original post: each layer is a separate camera exposure, then processed in Lightroom.
    Thanks,
    Sonny

  • IPv6 ACL masks

                       Can you mask random bits in the IPv6 address in an IPv6 ACL?  from the documentation it looked like only the /network boundary was allowed. 

    Hi,
    as far as i know it's not possible as we don't use inverse masks like in IPv4 ACLs but the prefix-lenghts.
    Regards.
    Alain
    Don't forget to rate helpful posts.

Maybe you are looking for