Photoshop :: How To Get Histogram To Give Accurate Reading
Apr 24, 2012
I use the histogram feature in PS to figure out how many square feet of yarn I will use in a rug that I am making (I work as a rug designer). I am running into a problem with this which is scary because my numbers have to be accurate.
As an example, I may have a 9x12 (inch--this is later blown up to feet using a transparency) drawing. In the drawing there may be 45 organic looking shapes that will be green. I use the magic wand tool and choose all of these green shapes. What I am noticing is that once I get to a certain number (not always consistent) in the histogram reading it will all of a sudden change to a different number and go to (for example) Cache 3. Because of this I have no idea if my histogram reading is accurate.
Is this some sort of memory issue? How do I prevent this from happening so that I can get an accurate heading?
Does anybody knows wich was the first PS version to include this window? silly question but I cant find it in version 7, I think the one with the eye in it´s logo.
I sometimes see a razor thin line on the right edge.
Is that clipping?
I mean it very clear when I see the mountain slamming up to the right, but many times I see a normal mountain rise and fall, and then seem to see this razor thin blue green or red line on the right edge.
I am using the histogram function in PS CS4 for Windows. I am using the magic wand tool to choose numerous "green" elements (for example). As I choose more and more elements, the pixel amount goes up in the histogram table. For some weird reason, when I choose enough elements to hit around 50000 pixels, the amount reverts to 12000 and goes to "cache level 2". I need to be able to have a total of all my elements for the project I'm working on. Is this a memory issue? How can I increase the cache?
Why the histogram for a gradient is not flat, as I guess it should be? Or, how to make a gradient that results in a flat histogram (that is, with the same number of pixels for each level)? The screen capture annexed should clarify the subject.
For a research project, I am calculating the area of the cytosol of a cell by finding the total cell area and subtracting the total nuclear area. I have been using the lasso tool to select the boundaries and then the histogram to measure the total pixels in that selection area. Proportionately, the nuclear pixel area should always be smaller than the total cell area since the nucleus is inside that cell. Most of my measurements have been accurate, but I started to run into the problem in which occasionally the nuclear pixel area is larger the total cell area. This does not make sense, which means that Pixel # that the histogram records must not actually be counting every pixel. I have tried to do some reading online and it sounds like the histogram is made based on different color intensities. If that were the case, that histogram pixel count is not the total area of the selection but rather only the pixel count that is being used to calculate the histogram.
I have tried changing the Channels from grayscale to RGB, etc. to see if that might use more of the pixels but there is no difference. What is the difference in these measurements and how can I make sure that the histogram counts every pixel?
Also, once I have that issue figured out, to convert my pixel count to a cell area, do I use the equation
A=P/s^2? A=real cell area P=pixel count S=linear pixel/cm.
I have a bar scale from the microscope on the bottom of each image, thus I can accurately find this variable. I would have to square it since I need the area. Does that look correct?
On a number of tutorials in Photoshop User and elsewhere I've noticed when the curves dialogue is brought up there's a histogram laid in the background of the curves manipulator, but I don't have that. How do I get that histogram? I use CS2.
When using the Hide function on the Crop tool I understand the pixels are hidden and the info retained. My question is does the Histogram palette look at the 'big picture' on the Hide function, and the histograms in either Levels or Curves only look at what is visible?
I'm guessing this is so, but was wondering if someone could verify it. I ask because of the difference in the histograms when using Levels or Curves compared to the Histogram palette.
How do I get Photoshop to open with floating windows and the histogram in compact RGB mode? I have to reset this every time I open a new photo. I can't believe how hard it is to change modes in the histogram.I have to undock it, change it to expanded view, change the mode, change it back to compact view and redock it. This made sense to someone? I tried saving the workspace.
I am trying to collect the mean, median, and mode of the RGB color values for a lot of different images.. Instead of just exporting the histogram raw data, I would rather just export what you see in the 'statistics' window when you open the histogram window.
Also, if I just wanted to transcribe it myself, I am not even able to keep the histogram window open while typing the data in excel.. So I constantly have to click back and forth (or just get better memory)..
I was investigating something else, and I saw something not working... I'm under the distinct impression that the Histogram panel should automatically update after every operation. Having the Histogram panel displayed full-time on the screen, it should always be up to date.
However, when I Dodge or Burn or even paint color on an image, the Histogram is not updating. If I select one of the History states I've just created, it updates.Consider this simple sequence of operations:
I'm able to reproduce this failure in Photoshop CS5 as well, BUT NOT IN CS4 (it updates in Photoshop CS4 after every painting operation), so clearly it's not a new bug, though somehow I've managed not to notice it in my years of using Photoshop CS5.
Is it broken like this for everyone in Photoshop CS5 and 6?Could this be some twisted attempt to try to optimize painting performance? If so, why isn't there an option to allow a user to request it to update on every operation on a fast computer with cores out the wazoo?
I prefer leaving my histogram in Photoshop CS6 in RGB mode, yet everytime I close the program and re-open photoshop, it defaults to Colors when I open a new document. How to get it to retain the RGB readout as a default?
I found out on cs5 there is a histogram equalizer with in hdr toning...I also found out that there are plugins for histogram equalizers. I did download one called kamflex it was ok but it was noisy. From my learned friends on this site can you recommend others and if so where is the best place to get them.
I'm currently recording the median luminosity and standard deviation of luminosity values in various photographs. This has been an ongoing project so I've been working on it for probably the last 4 months. Today I resumed my work and had to go back and check a previous photo that I had already recorded luminosity values for and noticed that the luminosity values that I had originally recorded were different than the values I'm seeing today in the histogram.
The attached picture shows the histogram I'm using (and have been using since I started this project). It is showing a median luminosity and standard deviation of luminosity for a photo that originally gave me this median luminosity value: 75 and this standard deviation: 27.87
I accidentally changed some setting in photoshop that affected the luminosity readings, or if the luminosity values of a photo are estimated by photoshop and thus aren't always the same etc. ?
Recently I noticed the histogram in PS4 displaying color channels instead of luminosity. And all three RGB colors seem to spike off the top of the window. Is there a way to only display the luminosity histogram curve? Also, how often would be considered normal to have to re-set preferences?
Since I capture my images in RAW, when I open them in Adobe Camera RAW (via Elements 11), what information is displayed in the image and the histogram I see?
Is it showing me the jpeg created in the camera? If so, the jpeg settings in my camera are not only important in viewing the LCD and the histogram in my camera at the time of capture. They would also be important in viewing my image when it first opens in Adobe Camera RAW.
I'm having trouble getting my 3D lighting to look, well, believable in PS CS5 Ex. I've moved them around, tried different types of lights, and nothing seems to give me proper shadow contrast and glare and shine on my material. Here is a screen of a dining room setting I'm building (preliminary stage) by combining 2D and 3D elements.
The corner hutch on the right is the 3D piece and the two on the left are 2D. The walls, ceiling and floor are also all 3D as well.
I am working on a research project that involves evaluating the relative abundance of various colors in a leaf. The leaves that I am working with have three distinct sections of color (green, burgundy, and coral).
I have scanned images of the leaf samples on a flat bed scanner (all with the same quality) and am using the magic wand tool to determine the total pixel count of the leaf and the total pixel count for each individual color. With this data, I determine the relative percent of each color within the leaf. Code:
When I set the opacity of a layer to, say, 50%, it will always go down one percent below, to 49% I'm not trying to be too picky here, but it's irritating when the opacity of the layer will always slide down one percent from what I set it as. So 68% becomes 67%, and so forth.
I have used Photoshop CS4 and and CS6 Beta and have never experienced this odd problem. When I set the exact opacity or fill, it will stay there. But with Photoshop CS5, it doesn't. I know it's not a huge problem, but like I said, it gets a bit annoying after a while, especially when I'm recording actions..
My neighbor brought a problem to me which I could not solve. He is running Photoshop CS3 10.0.1 on XPSP2. When he crops something at an angle, the resultant image is way off -- it is not what is within the crop mark. Any idea what is happening here?
I'm using the Adobe Photoshop CS3 trial on a Windows Vista machine - I've been using it for a couple days and I've noticed a number of times that the image in the preview window doesn't match what I get (usually after using image adjustment tools like Layer, Contrast/Brightness, or Curves - haven't noticed it so much with Filters, but haven't been using those as much yet either).
I have a bunch of wooden colour samples which need scanning for a website, but have found the scan result are usually off from the real thing. Understand that it's not going to be possible to get a 100% match, would would like to have something which is quite close to how it looks in real life.
there are text labels on the wood in white, after scanning the text appears as colour #a2b5c2 (blueish-grey), the wood itself is a dark brown but appears much lighter. have managed to find a picture of how it should look, compared to the one I scanned.
I like to set lines for cropping on the canvas. The vertical ruler is perfectly accurate. The horizontal ruler is off by alot. This is on cs4. The canvas size is adjusted to be A2 (420x594mm) The crop marks are with the ruler in inches to 16x20.
I'm working on a web page layout project on Adobe Photoshop CS and I was wondering: What effects should I apply to get a look for my top like those ones (I've got the shape)
I'm using Photoshop CS4 and am trying to cleanly select a flower. The flower has a white background that I'd like to remove; I've used the Select > Color Range. However, it still leaves rough edges around the flower's petals. This becomes apparent when I drop a black background behind the flower -- it has fuzzy edges that needed to have been selected and removed.
how to cleanly remove the background and not have the jagged edges?
I finding problems in trying to align my buttons in Photoshop with equal space between the buttons . Aligning web buttons in Photoshop.
In illustrator i have a method with the snap to point(snaps the object to nearest vertices i can then align the buttons with equal space, However the snap to layer. does not seem to be accurate in Photoshop.
Using PS CS5.1, converting a large space image to sRGB for web use does not give accurate render in actual browser. This is a common problem, but usually there are a couple of simple user errors that lead to this, and it usually means a less saturated image. This, however, seems unlikely to be user error, as I've tested it with a freshly created, sRGB image, with simple gradient, outputting it with embedded profile (non-embedded gives identical results in browser), and it becomes overly saturated.
The interesting, and probably all telling thing, is that viewing the optimized web version with Monitor Color selected in the preview gives what my browser actually shows me. Likewise, soft proofing using my Monitor RGB gives the same image as my browser.
I'm on WinXP x64. Browser is Firefox, and I've tried all three color management settings with no change, and also same results with Chrome browser.
This grad is in the ProPhoto space, converted during save for web. Color is a good match, with a slight shift, not unexpectedly. Note, preview is with Internet Standard RGB.
Same grad, this time with the preview set to Monitor Color. There is quite a saturation increase. This is what my browser actually shows me. I do not have desaturate colors selected in my color settings.
