From that picture I want to delete all instances of that specific color without having to go manually each pixel at a time.
Thanks
You can use Select / Select Similar to get a selection of all of the pixels with that colour, but bear in mind that Select Similar is affected by the Tolerance setting of the Magic Wand (W) tool.
So, first select the Magic Wand and set the tolerance to zero, then select one of the pixels you want to delete (with Marquee (M) and Edge set to Hard for example), then run Select / Select Similar. You can use the Paint Bucket (G) to replace the selection with whatever colour you want.
Of course, if you do want to catch pixels which aren't exactly the same colour, you can just set the Tolerance slightly higher.
Related
I have sRGB images with color casts. To remove it manually I usually use Photoshop Level Adjustments. Photoshop also have tools for that: Auto Contrast or even better Auto Tone which also takes shadows, midtones & highlights into account.
If I remove the cast manually I adjust each of the RGB channels individually so that the darkest pixels are set to pure black and the lightest to pure white and then redistribute all other values (spreading the histogram). This is a simple approach but shows good results for my images.
In my node.js app I'm using sharp for image processing which uses libvips as its processing engine. I tried to remove the cast with .normalize() but this command works on all channels together and not individual for each of the RGB channels. So it doesn't work for me.
I also asked this question on the sharp project page. I tested the suggestion from lovell to try it with hist_local but the results are not useable for me.
Now I would like to find out how this could be done using the native libvips. I've played around with nip2 GUI and different commands but could not figure out how it could be achieved:
Histogram > Equalise Histogram > Global => Picture looks over saturated
Image > Levels > Scale to 0 - 255 => Channels ar not all spreading from 0 - 255 (I don't understand exactly what this command does?)
Thanks for every hint!
Addition
Here is a example with pictures from Photoshop to show what I want.
The source image is a picture of a frame from a film negative.
Image before processing
Step1 Invert image
Image after inversion
Step2 using Auto tone in Photoshop (works the same way as my description above about manually remove the color cast)
Image after Auto Tone
This last picture is ok for me.
nip2 has a menu item for this.
Load your image and mark a region on it containing the area you'd like to be neutral. It can be any lightness, it doesn't need to be white.
Use File / Open to get the file dialog and you should see the image loaded in your workspace as a thumbnail.
Doubleclick on the thumbnail to open an image view window.
In the view window, zoom and pan to the right spot. The user guide (press F1) has a section on image navigation.
Hold down CTRL and click and drag down and right to mark a rectangular region.
Back in the main window, click Toolkits / Tasks / Capture / White balance. You should see something like:
You can drag an resize your region to change the neutral point. Use the colour picker to set what white means. You can make other whites with (for example) Colour / New / Colour from CCT and link them together.
Click Colour / New / Colour from CCT to make a colour picker from CCT (correlated colour temperature) -- the temperature in Kelvin of that white.
Set it to something interesting, like 4800 for warm white.
Click on the formula for A5.white to edit it, and enter the cell of your CCT widget (A7 in this case).
Now you can drag the region to adjust the pixels to set the neutral from, and drag the CCT slider to set the temperature.
It can be annoying to find things in the toolkit menu. There's a thing for searching toolkits: in the main window, click View / Toolkit browser. You can enter something like "white" and it'll show related toolkit entries.
Here's another answer, but using pyvips and responding to the previous comments. I didn't want to delete the first answer as it still seemed useful.
This version finds the image histogram, searches for thresholds which will select 0.5% and 99.5% of pixels in each image band, then rescales the image so that those pixel values become 0 and 255.
import sys
import pyvips
# trim off this percentage of pixels from the top and bottom
trim_percent = 0.5
def percent(hist, percentage):
"""From a histogram, find the threshold above which lie
#percentage of pixels."""
# normalised cumulative histogram
norm = hist.hist_cum().hist_norm()
# column and row profile over percentage
c, r = (norm > norm.width * percentage / 100).profile()
return r.avg()
image = pyvips.Image.new_from_file(sys.argv[1])
# photographic negative
image = image.invert()
# find image histogram, split to set of separate bands
bands = image.hist_find().bandsplit()
# for each band, the low and high thresholds
low = [percent(band, trim_percent) for band in bands]
high = [percent(band, 100 - trim_percent) for band in bands]
# rescale image
scale = [255.0 / (h - l) for h, l in zip(high, low)]
image = (image - low) * scale
image.write_to_file(sys.argv[2])
It seems to give roughly similar results to the PS button. If I run:
$ ./autolevel.py ~/pics/before.jpg x.jpg
I see:
In the meantime I've found the Simplest Color Balance Algorithm which exactly describes the problem with color casts and there you can also find a C source code.
It is exactly the same solution as John describes in his second answer but as a small piece of c-code.
I'm now trying to use it as C/C++ addon with N-API under node.js.
I imagine there is probably going to be an easy solution for this in GIMP, but I for the life of me can't figure it out.
I'm using the color picker tool with the use info window selected to verify pixel values.
Basically, I have some pixels in an image that I need to zero out. By that I mean I want the RGBA values to all be set to 0.
I attempted to:
use the rectangular select tool to select the group of pixels
use bucket fill to set the pixels to black with opacity set to 0.0
Then, to verify it was done correctly, I use the color picker to test the value of the rectangle I just filled.
Unfortunately, it seems to just contain the previous value. What am I missing here?
The "opacity" of the bucket-fill is the opacity of the paint, not the opacity of the resulting pixels. In other words the less opaque it is, the less visible the result. What you want to do is bucket-fill selection with black, then [delete].
While using Delphi Seattle 10 and Steema TeeChart Pro VCL FMX 2016.18, I am looking to Highlight a Selection of a Line Graph (multiple series) in the way that Zooming allows / makes a square around a highlighted selection of a Line Graph to indicate which part of it to zoom into (as long as the onmousedown action is in progress).
The purpose of this would be to allow the selection to remain highlighted while the mouse is no longer being clicked, to potentially "Delete" the highlighted Data points. All I need this for is to obtain the (X0 Y0 X1 Y1) values to possibly obtain the CalcPosPoint(X) and remove all the points inside. The data is currently obtained through a Record Struct (Memory Mapped) file, and it will there for be used to set/check for a property "deleted" to indicate on the next redraw of the graph which rows to completely ignore and which to continue printing.
I hope to be able to do this (select from 1 chart), and have it simultaneously draw on multiple graphs. I have tried to look for an example of this feature through the use of TSelectorTool (FMXTee). One of the pages I found referring to such a tool is Interactive data point selection as well as Multiple selections with Selector Tool
And my second question has to do with TeeCharts directly. Where would I find fmx240.bpl as TeeChart_Pro_Firemonkey_Demo.exe requires this file in order to run? I did manage to copy vcl240.bpl from "Embarcadero\Studio\18.0\bin" and put it into "Embarcadero\Studio\17.0\bin"
[Edited]
I have managed to capture / create a sample code (MVCE) from which I can now select a portion and create a square around a particular sample of graph lines.
The control graph right now is the bottom graph (Chart5). If anyone is interested in seeing the code, I have put up a pastebin sample.
PasteBin Sample Code
And a TeeCharts.tar.gz is accessible to anyone who wishes to see a sample of the code, as well as the data sample.
filetolink.com Source Files
I no longer feel the need for mathematical equation to differentiate the top graphs from the bottom (because the bottom axes are automatic where as the top are defined). I intend to only use the space which is adherent to the visible space, and do not intend to extend in either direction (left or right). That means at this point the size of the graph does not matter, because once I over populate the charts above, the position in the bottom graph would become irrelevant, and therefor I do not intend to use the bottom chart.
The next step is to save the positions of the boxes so that they can reappear when the graph is shift from left (past data) to the right (live data). And then uses the buttons above to make the appropriate action to the graphs.
I would like to know what way would be the most sufficient way to record the positions of the rectangles, so when the chart is shifted (via the ScrollBar1), the rectangles are moving with the direction of the scrollbar. But I'm sure I can achieve that.
I think I have found a solution. The red squares are only prevalent for the visual aspect, they can be drawn on, I don't need to do anything special with each chart, as I already know what the X0..Y1 parameters are, they are known from the initial chart. The problem h/e has to do with the initial chart. As long as the screens are all full, I can zoom in correctly w/ alignment with on all the charts (ZoomRect/Rectf(X0..Y1))
But what kind of equation would it take to adjust the charts that are not in the same zoom / max / min when the Chart5.Axes.Bottom.Automatic = True?
From there I just simply have to disable the immediate zoom feature, and allow buttons to become functional, to decide what the next course of action would be.
I have an image with a group of cells and I need to count them. I did a similar exercise using bwlabel, however this one is a bit more challenging because there are some little cells that I don't want to count. In addition, some cells are on top of each other. I've seem some MATLAB examples online but they all involved functions that aren't available. Do you have any ideas how to separate the overlapping cells?
Here's the image:
To make it clearer: Please help me count the number of red blood cells (which have a circular shape) like so:
The image is in grayscale but I think you can distinguish which ones are red blood cells. They have a distinctive biconcave shape... Everything else doesn't matter. But to be more specific here is an image with all the things that I want to ignore/discard/not count highlighted in red.
The main issue is the overlapping of cells.
The following is an ImageJ macro to do this (which is free software too). I would recommend you use ImageJ (or Fiji), to explore this type of stuff. Then, if you really need it, you can write an Octave program to do it.
run ("8-bit");
setAutoThreshold ("Default");
setOption ("BlackBackground", false);
run ("Convert to Mask");
run ("Fill Holes");
run ("Watershed");
run ("Analyze Particles...", "size=100-Infinity exclude clear add");
This approach gives this result:
And it is point and click equivalent as:
Image > Type > 8-bit
Image > Adjust > Threshold
select "Default" and untick "dark background" on the threshold dialogue. Then click "Apply".
Process > Binary > Fill holes
Process > Binary > Watershed
Analyze > Analyze particles...
7 Set "100-Infinity" as range of valid particle size on the "Analyze particles" dialogue
On ImageJ, if you have a bianry image, watershed actually performs the distance transform, and then the watershed.
Octave has all the functions above except watershed (I plan on implementing it soon).
If you can't use ImageJ for your problem (why not? It can run in headless mode too), then an alternative is to get the area of each object, and if too high, then assume it's multiple cells. It kinda of depends on your question and if can generate a value for average cell size (and error).
Another alternative is to measure the roundness of each object identified. Cells that overlap will be less round, you can identify them that way.
It depends on how much error are you willing to accept on your program output.
This is only to help with "noise" but why not continue using bwlabel and try using bwareaopen to get rid of small objects? It seems the cells are pretty large, just set some size threshold to get rid of small objects http://www.mathworks.com/matlabcentral/answers/46398-removing-objects-which-have-area-greater-and-lesser-than-some-threshold-areas-and-extracting-only-th
As for overlapping cells, maybe setting an upperbound for the size of a single cell. so when you have two cells overlapping, it will classify this as "greater than one cell" or something like that. so it at least acknowledges the shape, but can't determine exactly how many cells are there
I need to modify the focus-box's border color of TVirtualStringTree,
just like this pic:
You can't control the color of the dotted focus rectangle. That's determined automatically by inverting the color of whatever it's drawn on. The OS provides — and the tree control uses — an API for that. (You could edit the source code and replace calls to DrawFocusRect with your own function, if you want.)
If you're talking about the color of the whole node, then first check to make sure the toUseBlendedSelection paint option is set the way you want it. It defaults off, but since it makes the selection rectangle look cool when dragging a box around items, you might have turned it on without realizing what it does to ordinary selected nodes, too.
If that's not it, then adjust one of the values in the tree control's Colors property, probably either FocusedSelectionColor or UnfocusedSelectionColor. But please don't make such a change lightly; the user has chosen the selection color through the OS options, so you probably shouldn't change it. If you do use a different color, make sure the text is still readable against whatever new color you select.
You can set treeview's option toHideFocusRectangle to true and paint your focus rectangle by yourself in one of several paint events (basically it is enough to use OnBeforeCellPaint).