I have a picture with a black background and gray objects and I want to filter out the objects. But the light incidence makes it impossible to just look after a color. It will either filter not the whole object or it will filter as well the background.
If some can give an hint or an example in C# it would be nice.
sory because i'm using VB.NET but hope I can help you
Dim myBitmap As New Bitmap("Grapes.jpg")
Dim pixelColor As Color = myBitmap.GetPixel(X, Y)
if pixelColor = Color.Black
myBitmap.SetPixel(X, Y, Color.Blue)
If in objects have black color. I guess you have to change others way to get the object like save object's area.
Without any example image is hard to guess. But for start you should look into histogram equalization. This method enables to balance the lightning in the image.
Wikipedia has a nice example of what hist equalization is capable of.
Related
I have a grayscale photo that I am trying to colour programmatically so that it looks 'real', with user input 'painting' the colour (eg red). It feels like it should be simple, but I've been stuck trying a few ways that don't look right, so thought I'd ask the community in case I've missed something obvious. I've tried the following
Converting to HSV, and combining the "Hue" and Saturation from the colour selected by the user, with the "Value" from the image.
Building a colour transformation matrix to multiply the BGR values (ie R = 0.8R + 1.1G + 1.0B). This works well for 'tinting', and adds a nice pastel effect, but doesn't really keep the depth or boldness of colour I want.
(favourite so far - see answers) multiply RGB from colour channel by RGB of image.
To add to the comment by user Alexander Reynolds, the question that you're asking is a known open research problem in the field of computer graphics, because the problem is under-constrained without using statistical priors of some sort. The state of the art in the CG community is found here, presented at SIGGRAPH 2016.
http://hi.cs.waseda.ac.jp/~iizuka/projects/colorization/en/
Also see:
http://richzhang.github.io/colorization/
I've had another think and play with photoshop, and implemented a multiply blend mode on BGR space to get an ok result.
Implemented in java
Mat multiplyBlend(Mat values, Mat colours) {//values 1 channel, colours 3
//simulates BGR Multiply blend mode
ArrayList<Mat> splitColours = new ArrayList<Mat>();
Core.split(colours, splitColours);
Core.multiply(values, splitColours.get(0), splitColours.get(0), 1/255.0f);
Core.multiply(values, splitColours.get(1), splitColours.get(1), 1/255.0f);
Core.multiply(values, splitColours.get(2), splitColours.get(2), 1/255.0f);
Mat ret = new Mat();
Core.merge(splitColours, ret);
return ret;
}
We are developing an app where we need to crop an image according to the selecting object area. User will draw a line and we need to select the object and crop it .This crop need to be like the app: YourMoji
So far we have tried to get the color of the pixels along the line and then comparing those with the color of every pixel in the image and making a path from it to clip the image. But the almost going no where.
Is it possible through this way to crop an image or we are going in the wrong way? Can anyone provide a way to do this Or suggest a way to modify the way we have worked so far? Any advice and suggestions will be greatly appreciated!
Thanks in advance.
I guess what you want is the image segmentation algorithm called Graph Cut.
Here are two Github repositories, hope these would help:
GraphCut
GrabCutIOS
I'm not exactly clued up on image manipulation, but the first algorithm that comes to mind is something like this:
Take the average of the pixels in the line (as you have)
Since you appear to want faces, you might want to weight reds and blues over green. Not much green in faces of any skin tone.
For each pixel, if the colour is within a given threshold outside of your selected average, remove it / make transparent.
Perhaps the closer to the original line (or centroid), the less strict the threshold becomes.
I'd then provide the user with some tools for:
Sensitivity: how large the threshold is
Eraser: to remove parts of the image that your algorithm missed
Paintbrush: to replace parts of the image that your algorithm incorrectly removed.
I am using the canvas draw functions drawrect and filltext to draw onto a Tbitmap but I don't want the results antialiased. Anyone know how to do that ?
Working with OSX and Delphi XE3 (but have XE4 and XE5 if needed)
Is the problem:
the bitmap you create seems to have anti-aliasing present in the data?
or have you got a good bitmap and want to disable anti-aliasing in the viewer/display?
If it is the former, have you checked that the anti-aliasing is actually present in the bitmap, and not introduced by your viewer?
In the past I've found it useful to draw a black-on-white test pattern, and display the image at 1:1 scale. Irfanview is a nice tool for viewing at 'true' scale. Then use a loupe/peak/lens to get a close-up of the actual pixels.
Black-on-white test patterns are particularly good since you should be able to see (hopefully) that the R,G and B sub-pixels are all equally illuminated when there is no anti-aliassing present. If you draw a black-on white pattern and you get solitary bright sub-pixels then you've definitely got anti-aliassing (or some other form of corruption!).
My experience has been that image viewers often do interpolation for you, and it can be tricky to see what is going on unless you look at the actual bitmap data or have a close-up look at the unscaled image...
Hi in the drawBitmap method you need to set HighSpeed parameter to "True", in the sample below:
NewBitmap.Canvas.DrawBitmap(SmallBmp, RectF(0, 0, SmallBmp.Width, SmallBmp.Height), RectF(0, 0, NewBitmap.Width, NewBitmap.Height), 1,**True**);
rgds
Ivan
I have been working with OpenGL in iOS, and setting the colors with glColor4f(r,g,b,a) and then drawing my own color on a white UIImageView. I basically have a brush, which is then moved around my user's touch, and then it paints the color onto the canvas. But this color needs to be water paint (like smudged color)
Does anyone understand/knows how to get a water color like this app does, and how the background UIImageView has a texture on it?
https://itunes.apple.com/us/app/hello-watercolor/id539414526?mt=8
or checkout water paint in this. http://www.fiftythree.com/paper
I created a bounty on this as I am really having a hard time to grasp how to derive such smooth flowing colors out of the normal colors. Even if you guys point me in the right direction, or to some sample code on how I can get the effect of water-paint, it would be really helpful ^_^
And as a bonus, it would be also be helpful if you can point out to me how to get canvas on which it is painted on looks realistic, and blended with the paint? Does Blending/GLSL have to do with any of this?
Is there any sample project on this?
If you are still struggling with the basics of getting realistic looking water colors working, you may want to experiment/prototype in photoshop first.
http://www.zoepiel.com/tutorials/watercolor/ shows some very effective tricks for creating watercolor images with simple tools.
The most interesting one is to multiply a group of watercolor layers with a greyscale watercolor paper image. The texture of the paper makes some parts remain white, and other parts saturate with color, just like real watercolor.
Each layer remains 'wet' in the sense that the colors within it blend, but the layers are 'dry' with respect to each other.
She also explains some of her brush and blur settings and shows what they do.
Once you can produce the desired effect in photoshop, you'll have clear specifications of what you want to do and you'll be quite a bit closer to programming it out.
Looking at the examples you posted, it looks like they are using a simple Gaussian Blur with a radius of double your brush size. This may be an incomplete solution, but it's at least the first level.
I have a project to customize clothes ,let say a t-shirt, that have following features:
change colors.
add few lines of text ( <= 4) and change the font from a list.
add image or photo to the t-shirt.
rotate the t-shirt to custom back side.
rotate the image and zoom in/out.
save the result as a project locally and send it to a webservice ( i think to use NSDictionary/json ).
save as an image.
so my question is :
Should I use multiples images to simulate colors changes. Or should I use QuartzCore ( I am not an expert in QuartzCore but if I have to use it I'll learn). Or is there a better approach for this ?
Thank you.
The simple way to do this is to render the T-Shirt image into a CGContext, then walk the rows and columns and change pixels showing a "strong" primary color to the desired tint. You would take a photo of a person wearing a bright red (or other primary color) t-shirt, then in your code only change pixels where the red color has a high luminance and saturation (i.e. the "r" value is over some threshold and the b and g components are low).
The modified image is then going to look a bit flat, as when you change the pixels to one value (the new tint) there will be no variation in luminance. To make this more realistic, you would want to make each pixel have the same luminance as it did before. You can do this by converting back and forth from RGB to a color space like HCL. Apple has a great doc on color (in the Mac section) that explains color spaces (google 'site:developer.apple.com "Color Spaces"')
To reach your goal, you will have to tackle these technologies:
create a CGContext and render an image into it using Quartz
figure out how to read each pixel (pixels can have alpha and different orderings)
figure out a good way to identify the proper pixels (test by making these black or white)
for each pixel you want to change, convert the RGB to HCL to get its luminance
replace the pixel with a pixel of a different Color and Hue but the same Luminence
use the CGContext to make a new image
If all this seems to difficult then you'll have to have different images for every color you want.