The ImageList has a method named "Draw":
imageList.Draw(graphics, bounds.X, bounds.Y, bounds.Width, bounds.Height, imgIndex);
I use this method to draw an image on a graphics object of a PrintDocument. When using the original image size (16 x 16 pixels), the image is drawn correct. If however, I change the bounds size, nothing is drawn. Even changing the size to 32 x 32 (double size) has no effect. Nothing is drawn. I need to change the drawn size because of the different dpi ... Where am I gong wrong ?
Edit: The solution seems to be simply to use the g.DrawImage method instead. Why imageList.Draw() doesn't draw is still a mistery to me ...
g.DrawImage(imageList.Images[imgIndex], bounds);
ImageList.Draw() is a bit unusual, it takes advantage of the built-in support that the native image list code inside of Windows has for rendering an image in the list. This is an optimization, it avoids the cost of converting the internal image as stored in the native image list back to a managed Image object.
One side-effect however is that this drawing happens without regard for any of the transforms that were applied to the Graphics object. A 16x16 image in the list is going to be rendered as 16x16 pixels on paper. Which is indeed a bit hard to find back, printers have very high resolution (600 dots per inch is typical), that image turns into a decimal point.
Image lists were really meant to be the source of images for the TreeView and ListView controls, it is not a good general purpose collection object for images. Like a List<Image>. Your workaround is good, the Image property converts the internal bitmap back to a managed Image, Graphics.DrawImage() will then scale it appropriately to get a size on paper that's close to the size on the screen. However with the graininess you get from making an image 6 times larger. Note that you should Dispose() that object.
Related
I'm creating an image with some text and using TextureBrush for draw the text along a line repeatedly. It is working fine on the screen. when i want to print it, it looks very bad.. I've tried to create the image bigger (relative to the dpi differences) and set its resolution as the resolution of the Graphics object (For printing it is higher). Printing the image as it is looks good.. but as TextureBrush not so good.
I'm attaching all the prints - Tried to print it to PDF printer - same results as real printer - so no problem there.
first try before changing anything
Drawing the image using graphics.DrawImage(...) (The image contains The letter 'A' that I've drew in)
Printing TextureBrush
At this time it was clear that i have resolution problem so I've created my image bigger and in better resolution (as the printer dpi)
Drawing the image using graphics.DrawImage(...)
Looks perfect - Exact size and good quality. graphics.DrawImage(...) drew the picture with consideration of its size and resolution.
Now I've used this picture in my textureBrush. The result looks like this
It is bigger because the image itself is bigger - But why it does not consider resolution like graphics.DrawImage(...)..
Anyway i've decided to continue and scale down the image using TextureBrush.ScaleTransform(...) - The results looks like that
This is the best that i've reached so far.. I think the main problem is the TextureBrush that does not consider the resolution of the image.
I would really prefer to stick with the TextureBrush way (And not drawing image by image with clipping and repeating), cause it is very complex code, and complex drawing
Help anyone ?
your help is much appreciated. I am using C# and EmguCV for image processing
I have tried noise removal, but nothing happens. I also tried image median filter, and it only works on the first image, but it does not work on the second image. It only makes the second image blurry and the objects larger and more square-like.
I want to remove obviously distinct objects(green ones) in my image below so that it would turn all black because they are obviously separated and are not grouped unlike the second image below.
Image 1:
At the same way, I want to do it in my image below, but remove only those objects -- (the black ones) -- that are not grouped/(lumped?) so that what remains on the image are the objects that are grouped/larger in scale?
Image 2:
Thank you
You may try Gaussian Blur and then apply Threshold to the image.
Gaussian Blur is a widely used effect in graphics software, typically to reduce image noise and reduce detail, which I think matches your requirements well.
For your 1st image:
CvInvoke.GaussianBlur(srcImg, destImg, new Size(0, 0), 5);//You may need to customize Size and Sigma depends on different input image.
You will get:
Then
CvInvoke.Threshold(srcImg, destImg, 10, 255, Emgu.CV.CvEnum.ThresholdType.Binary);
You will get:
For your 2nd image:
CvInvoke.GaussianBlur(srcImg, destImg, new Size(0, 0), 5);//You may need to customize Size and Sigma depends on different input image.
You will get:
Then
CvInvoke.Threshold(srcImg, destImg, 240, 255, Emgu.CV.CvEnum.ThresholdType.Binary);
You will get:
Hope this help!
You should first threshold the image using Otsus method. Second run connected component analysis on the threshold image. Third go over all the component that you found and for the ones that have a size that is smaller than some min size delete it from the original image.
cvThreshold (with CV_THRESH_BINARY/CV_THRESH_BINARY_INV(choose according to the image) + CV_THRESH_OTSU) http://www.emgu.com/wiki/files/1.3.0.0/html/9624cb8e-921e-12a0-3c21-7821f0deb402.htm + http://www.emgu.com/wiki/files/1.3.0.0/html/bc08707a-63f5-9c73-18f4-aeab7878d7a6.htm
CvInvoke.FindContours (RetrType == External,ChainApproxNone)
For each contour that we found in 2 calculate CvInvoke.ContourArea
If area is smaller than minArea draw on the original image(The one you want to filter) the value you want for them(0 I suppose) in the original image using CvInvoke.DrawContours with the current contour and with thickness==-1 to fill the inside of the contour.
Quick question:
I have this 1000 x 1000 bitmap image:
and I use this routine to load it:
private BitmapSource initialBitmap = new BitmapImage(new Uri("C:\\Users\\...\\Desktop\\Original.bmp"));
Why after I load it, and right after I step over the above line, I see it as 800 x 800?
P.S I want it to be 1000 x 1000 and without using any Resize functions. It was working and suddenly it is 800*800 !
The values returned by BitmapSource.Width and BitmapSource.Height are not in pixels, but rather WPF's device-independent units, which are always 96 dpi. E.g.:
Gets the width of the bitmap in device-independent units (1/96th inch per unit).
If you want to know the actual pixel width and height, you need to use the PixelWidth and PixelHeight properties.
Your question isn't very specific, but if what you are actually concerned about is having the bitmap display at the same size in which it was authored, then the easiest solution is to make sure you author it at 96 dpi. Whatever program you're using to author the bitmap likely has a place where you can set the bitmap resolution. Typically this can be set with or without changing the pixel dimensions of the image (i.e. scaling the image larger or smaller); you want to do it without scaling the image, so that the pixel dimensions remain the same but the dpi changes to match what WPF is using.
Note that this still won't guarantee the bitmap displays at a specific pixel size. The display resolution can be and often is different from 96 dpi, in which case WPF will scale images to ensure that the physical dimensions of the image (i.e. the dimensions in inches, millimeters, etc.) are correct according to the information in the bitmap. For example, 960 pixels wide at 96 dpi means 10" wide. On a 120 dpi display, this means displaying the bitmap large enough so that its width uses 1200 display pixels.
If you want or need the bitmap to display at exactly the same number of display pixels regardless of the display resolution, then you'll have to set a transform where you display the image to reverse the effect of the scaling that WPF would otherwise do. This requires knowing the display resolution, of course.
Here are some other related Stack Overflow questions which you might find useful:
RenderTargetBitmap renders image of a wrong size
WPF for LCD screen Full HD
Screen Resolution Problem In WPF?
This is by design. Note the MSDN documentation for BitmapSource.Width/Height:
Gets the width of the bitmap in device-independent units (1/96th inch
per unit). (Overrides ImageSource.Width.)
Instead you should use the PixelWidth / PixelHeight property:
Gets the width of the bitmap in pixels.
A rather confusing choice or terms, imo, but there you go..
I have a Bitmap variable and I copy smaller 32x32 png files (loaded as Bitmaps) onto the bitmap. However, some png's are scaled up (always the same ones) and appear as 36x36 for example after copying. Almost as if some png's have another DPI or something? How can I prevent this?
Graphics g = Graphics.FromImage(destinationImage);
g.DrawImage(sourceImage, location); // sourceImage is sometimes larger than it actually is. On disk it is 32x32 but after copying it might be bigger...
g.Dispose();
I guess you are right about DPI, as it's stated in the documentation:
This method draws an image using its physical size...
I'm too lazy to make a test project, but I think Graphics.DrawImage(Image, Rectangle) with rectangle size equals to source image size will fix your problem.
The Image.Horizontal/VerticalResolution property matters. If it doesn't match the dots-per-inch setting of your monitor then the image is going to be drawn proportionally larger or smaller. This tends to be undesirable, use the DragImage(Image, Rectangle) overload to force it to display at exact 32 x 32 pixels.
My application is used to design airports for a flight simulator. Users can add one or more images as background. The image(s) can be sized accurately and then used as a template to lay down features such as runways, aprons and so on.
I use a third party graphics library (Piccolo) which has an image class (as far as I can see it is a simple wrapper for System.Drawing.Image).
So far I have done little except allow the user to add an image, size it and so on. It will be no surprise that users sometimes complain of poor performance. We tell them not to load large images (up to 100k seem OK) but don't stop them and 100Mb bitmaps have been used with horrible results.
I need to fix this in a couple of ways. First by converting any image they use to an efficient format (size vs definition) and second by ensuring that the loaded image is suitably sized for the dimensions - at the moment I don't do anything specific to deal with the resizing of say a 2000 x 2000 image to fit a 500 x 500 area of the display.
The default 1:1 display of the application represents 1m per pixel. Once the user has resized the image to fit accurately would I be right in thinking that the best resoultion for the image would be to resample it to that size? I am aware that if the user zooms in way past 1:1 which they will probably do then the clarity of the image will fall.
My ignorance of handling images is complete. I have looked at some image manipulation libraries (ImageMagick and the free version of dotIamge) first for converting the input image to a standard one and second for resizing -resampling. The truth is that they do far more than I need.
Any pointer much appreciated.
Yes, resampling so that the bitmap doesn't constantly have to be rescaled for every paint should make a big difference. The default Graphics.InterpolationMode makes pretty images but is not cheap.
Another biggie is the pixel format of the bitmap. Format32bppPArgb is 10 times faster than any of the others on most video adapters.
private static Bitmap Resample(Image img, Size size) {
var bmp = new Bitmap(size.Width, size.Height, System.Drawing.Imaging.PixelFormat.Format32bppPArgb);
using (var gr = Graphics.FromImage(bmp)) {
gr.DrawImage(img, new Rectangle(Point.Empty, size));
}
return bmp;
}