Develop Reference

What does MSPaint process to eliminate objects in background when PNG image is converted to 4-bit BMP image?

I opened a PNG image, clicked Save As, changed to 16 color Bitmap, and saved it.
Then, MSPaint warned about loss of information about transparent and image qualities and, I clicked OK.
As a result, letters behind the black glass object disappeared clearly like this image (Before->After).
By changing PixelFormat or removing transparent area on C# (.Net 4.6.2), I tried to implement this feature just like MSPaint, however, it wasn't removed clearly. In some way, Nothing changed.
Is that not about PixelFormat or ColorDepth?
Or, Is there a way to get rid of objects behind another on PNG?
What should I do to implement that?
EDIT 1
Thank you so much, #TaW. By following your method ApplyGamma, I could solve the issue.

c# W.P.F. image show tiff (just 1 page) blurry [duplicate]

I'm using some Images in my WPF applcation.
XAML:
<Image Name="ImageOrderedList"
Source="images/OrderedList.png"
ToolTip="Ordered List"
Margin="0,0,5,5"
Width="20"
Height="20"
SnapsToDevicePixels="True"
MouseUp="Image_MouseUp"
MouseEnter="Image_MouseEnter"
MouseLeave="Image_MouseLeave" />
But, they appear fuzzy.
Why doesn't that SnapsToDevicePixels="True" line prevent this problem?

You may want to consider trying a new property available now in WPF4. Leave the RenderOptions.BitmapScalingMode to HighQuality or just don't declare it.
NearestNeighbor worked for me except it led to jaggy bitmaps when zooming in on the application. It also didn't seem to fix any glitches where icons were sizing in weird ways.
On your root element (i.e. your main window) add this property: UseLayoutRounding="True".
A property previously only available in Silverlight has now fixed all Bitmap sizing woes. :)

Rather than using SnapsToDevicePixels, I instead used RenderOptions.BitmapScalingMode and they're now nice and crisp!
XAML:
<Image Name="ImageOrderedList"
Source="images/OrderedList.png"
ToolTip="Ordered List"
Margin="0,0,5,5"
Width="20"
Height="20"
RenderOptions.BitmapScalingMode="NearestNeighbor"
MouseUp="Image_MouseUp"
MouseEnter="Image_MouseEnter"
MouseLeave="Image_MouseLeave" />

+1 for Zack Peterson
I'm using .Net 3.5 sp1 and it looks like the most simple solution for a large number of fuzzy images.
It's not a big deal to specify RenderOptions in-place, but for 3rd-party components a style in app-level resource makes sense:
<Style TargetType="{x:Type Image}">
<Setter
Property="RenderOptions.BitmapScalingMode"
Value="NearestNeighbor" />
</Style>
Worked nicely when AvalonDock started to render blurry icons.

Using the UseLayoutRounding="True" on the root Window works in many cases but I encountered a problem when using the WPF Ribbon control. My application relies on Contextual Tabs that appear according to what the user is doing and when I set the UseLayoutRounding to True, the contextual tab would not show up and the RibbonButton's image neither. Also, the application freezes for many seconds and CPU fan starts to sing.
Using RenderOptions.BitmapScalingMode="NearestNeighbor" on my image corrected the image rendering issues (fuzzy and cropped image) and is fully compatible with the Ribbon Contextual Tabs usage.

RenderOptions.BitmapScalingMode="NearestNeighbor" works well most of the time. However, occasionally you'll get graphical glitches (in my case, 4 out of 5 images showed up fine, but the fifth had a slight distortion on the right edge). I fixed it my increasing the Image control's right margin by 1.
If that still doesn't fix it, try the Bitmap class control above that EugeneZ mentions. It's a replacement for the Image control and so far it's worked pretty well for me. See http://blogs.msdn.com/dwayneneed/archive/2007/10/05/blurry-bitmaps.aspx

use UseLayoutRounding=True to the top most element in your application

Make sure you save the image in the same DPI as your WPF application is working in, some image formats have this info stored as metadata. I don't know if this solves the problem but I've hade some problems because of this where images resized to 100% got bigger or smaller than expected.
Might be something similar.

I believe this is a bug (or at least it was). Check out this Microsoft support e-mail exchange page for some ideas to fix it.

I have found that the RenderOptions.BitmapScalingMode="NearestNeighbor" does not work for me. I'm using Windows XP x32 with DirectX 9.0c. As the actual rendering for WPF is done with DirectX, this could have an effect. I do have anti-aliasing turned on for XP with the following registry entries:
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Avalon.Graphics]
"MaxMultisampleType"=dword:00000004
"EnableDebugControl"=dword:00000001
However, turning aa off with these settings has no effect on the images. I think this only effects 3D Viewports.
Finally, I found that the blurring occurs with the text of TextBlocks as well as images. And the blurring only happens for some text blocks and images, not all of them.

I have found that no combination of the suggested workarounds would cure my seemingly random blurry image problem. I like many others cannot upgrade to .net 4 in order to use the UseLayoutRendering property.
What I have found to work:
Ensure your [original] image dimensions are multiples of 2. This seems to prevent some of the funky image scaling problems.
Sometimes I have also found that adjusting margins on images by a pixel or 2 can prevent the problem.

My first thought, reading the question, was you were blowing up the image too much, but that does not appear to be the case looking at the image you have of the app.
Second thought is color palette, but with black as one of the colors that is not rendering correctly, this is not as likely.
If you can fully rule out the two above, I am currently stumped.
As an experiment, you can try other graphics formats, but PNG should be fine. I will have to think it through some more to come up with a better answer.

I've tried to use the RenderOptions.BitmapScalingMode=HighQuality, seems like is causes some problems in Windows 8.1, so what i did was to run them through the tool called PngOut.exe
http://advsys.net/ken/utils.htm
Which reduces the header of the png, and also reduces the size, but without changing the image quality.
And now all my images are perfect! :-)

How to get a ScrollViewer to zoom in to see individual pixels?

I'm making an app for Windows 8.1 where it is important to be able to zoom in and examine images in detail. If I just open up the bitmap and zoom in it looks like.
However when I load the image into my app and use the ScrollViewer to zoom in I get.
As it appears to be trying to interpolate pixel values for some sort of anti-aliasing.
How can I get it so that when I zoom in it shows (as best it can) the exact pixels of the image? In particular I'm using the image as the background to a canvas which is contained in a scroll viewer.
I've looked around on here and MSDN and found a pair of related questions, but as yet they don't seem to have solved my exact problem.
A discussion on WPF
A similar issue with a canvas
Older related question on pixel art
A way to use bitmap encoding (which I couldn't get to work)
Similarly phrased question

There is no easy way to go about this, your best option is to use DirectX to render the image much larger so that you can mitigate the effect of WinRT automatically interpolating pixel values.
As someone explained on MSDN and based on this outstanding request I can't see any other way to accomplish this.
Use Win2D
Win2D is a DirectX inter-op library for WinRT. With this you can render the image at a much larger size, and then set the default zoom level for the scrollViewier to be very small. Because of this when you zoom in it will appear to be that you can see the individual pixels without any fuzzy/blurry interpolation because you will actually be seeing groups of 64 pixels or so all as one color. I couldn't find any way to actually override what kind of interpolation gets done so this seems to be the best method.
Download Win2D as a NuGet package using Visual Studio, Win2D's
quickstart guide does a good job explaining some of the setup
Set up your canvas and the draw event and use the DrawImage function to render the image larger
<ScrollViewer x:Name="Scroller" ZoomMode="Enabled"
MinZoomFactor="0.1" MaxZoomFactor="20">
<canvas:CanvasControl x:Name="canvas" Draw="canvas_Draw" CreateResources="create"/>
</ScrollViewer>
In the canvas_draw function.
canvas.Width = original.Width * 10;
canvas.Height = original.Height * 10;
args.DrawingSession.DrawImage(bitmap,new Rect(0,0,original.Width*10,original.Height*10), new Rect(0,0,original.Width,original.Height), 1.0f, CanvasImageInterpolation.NearestNeighbor);
Make sure to set your canvas to be larger as well
In your code behind set the default zoom of your ScrollVieiwer to be appropriate so your image appears to be the same size.
In the page constructor
Scroller.ZoomToFactor (0.1f);
Other Ways Which I Looked Into and Didn't Work
Making the canvas very large and using BitmapEncoder/BitmapDecoder with the interpolation mode set to NearestNeighbor, this introduced lots of visual artifacts even when scaled to a power of 2 size
Render options only appear to be usable in WPF and not WinRT
It may also be possible to use some image manipulation library to simply make the bitmap 10x or so as large and then use that, but I ended up using Win2D instead.

How to do Control.DrawToBitmap with transparency support?

At the moment I'm using Control DrawToBitmap method to capture my WebBrowser like following.
var bmp = new Bitmap(640,480, PixelFormat::Format32bppArgb)
var web = (System.Windows.Forms.Control)sender;
web.DrawToBitmap(bmp, Rectangle(0, 0, 640,480));
My Bitmap supports Alpha channel but this code doesn't save transparency.
Here is the webpage example :
http://jsfiddle.net/zPtPN/

EDIT 2: opacity on embedded browser
With CEF (Chromium Embedded Framework from Google) you should do as follows. This may or may not apply to the default .NET Internet Explorer control.
body
{
background-color: transparent;
}
To overlay this you have to render to a buffer that was cleared. That buffer IS NOT the final rendered raster but an intermediate in-memory buffer that retains VERY MUCH the alpha channel. As long as the buffer is cleared (filled with transparent pixels), you grab the buffer with the full ARGB32 channels and overlay it correctly, you should get what you want.
Best is, you try as far as you can go, then take a screenshot and post a new question specifying that you are using an embedded browser. Also specify the browser version because it will change from one machine to the other: Options for embedding Chromium instead of IE WebBrowser control with WPF/C#
The Bitmap might contain alpha channel information, but not all file formats support it. You should save the image as a *.PNG with ARGB32 lossless mode. A simple *.BMP file will not suffice.
Look at this answer to know not just how to save as PNG but also how to actually get the transparency right:
c# Bitmap.Save transparancy doesn't save in png
To grab transparency from the web page you can try this UGLY, CUMBERSOME, HORRIBLE technique that has tons of problems:
Use a unique color for the body background, like #ffe000. Render the page, grab it as before.
The transparent parts will show the body's background showing through.
At this point you can filter the image by setting its TransparencyKey to the color of the background -OR- by substituting all pixels of that color with a fully transparent pixel color (just change the alpha channel's value from 255 to 0).
Why this is horrible? Because the results will be ugly:
fonts are smoothed and will have shades of that color, so you can't get them partially transparent, they will retain opacity and look horrible much like gifs looked back in the ole'90 (they are called rendering artifacts).
if you use pretty CSS3 stuff like border-radius or box-shadow the same artifacts as above arise: border pixels with shades (anti-aliasing) will look horrible.
Ugly Example here.
So how can you remove these artifacts? You can't.
I highly recommend a completely different approach to your problem.
By the way, what do you want to achieve? Are you using CEF or other embedded browser technology that you want to overlay somehow?
Maybe there are other ways I can help you with....
EDIT: why the ffff <div> does not show
You set the style to:
background-color: transparent; opacity:0;
Now, the background of the <div> will be transparent and show what is behind (the <body>'s background-color). When you set opacity instead, you say to make the whole <div> (contained images and texts included) transparent. Setting it to 0 means totally invisible.

Listview icons show up blurry (C#)

I'm attempting to display a "LargeIcon" view in a listview control, however the images I specify are blurry. This is what I have so far:
alt text http://img220.imageshack.us/img220/1005/blurryiconsql3.jpg
The .png files are 48x48 and that's what I have it set to display at in the ImageList properties. There's one thing that I've noticed (which is probably the cause) but I don't know how to change it. Inside the "Images Collection Editor" where you choose what images you want for the ImageList control, it looks like it's setting the wrong size for each image.
alt text http://img83.imageshack.us/img83/5218/imagepropertiesmf9.jpg
As you can see the "PhysicalDimension" and the "Size" is set to 16x16 and not abled to be manipulated. Does anyone have any ideas? Many thanks!

Be sure to set ImageList.ImageSize to 48 x 48 too.

When adding a .PNG Icon format size the editor tends to pick the first entry size in that file, so it picks up the 16x16 entry and it's stretching that out. That's why you see the 16x16 in the properties there. As suggested, the support for PNG is poor, I'm often found myself rolling over to another format as well to avoid this.
You can open the file in Paint.Net if you need a free editor or something more fully featured like Photoshop or Fireworks and extract the exact size you want.

I'm not sure if its the problem in this specific case, but Microsoft support for the PNG format is generally poor. Try adding the images in .bmp format and they should display fine.

Check also the ColorDepth setting on your ImageList. I had a similar issue with a TreeView control, but after reading the previous posting regarding the size I found this setting, played around with it a bit and found that it greatly affects the way images from an ImageList are rendered. The higher the depth the better the quality.

Be sure to set the ImageList size to 48x48 px BEFORE you add the images.
If the ImageList is set to 32x32 and you add a 48x48 image, the icon is resized to 32x32. When you change the ImageList to 48x48 afterwards, the image is just resized again, thus losing quality and going blurry.
Also, Paint.NET (or Photoshop) can't open .ico files.
Visual Studio/.NET can handle 32-bit PNG images fine, the built-in image editor in VS is a bit lack-lustre though.