Does modern Windows provide some sort of hooks that would allow a developer to change pixel values before they reach the GPU/are sent to the display?
For example to convert the whole desktop to monochrome independent of the applications currenly displayed (perhaps even including games).
Something that could work along side an existing (closed source) display driver.
Related
So I have a big 32 inch display with a resolution of 1440p, and I want to set the DPI scaling to 75% instead of 100%. But I can't find any way to do so on multiple monitors.
I currently have:
Display 1 [2560 x 1440] (Main display I want to change)
Display 2 [2560 x 1440] (This one is 27 inches so it's fine as is)
Display 3 [3840 x 2160] (Set to 100%, fine as it is)
This trick (click me) changes DPI scaling via some registry keys (LogPixels & Win8DpiScaling), but when I use that trick it downscales display 3 instead of display 1.
Is there a way to get this to work? I see no reason for Microsoft to limit the scaling in displays.
Note: I have a 2070 super, all the displays are plugged into the GPU via displayport directly, with the latest avalible firmware at the time of writing (september 2021)
The tl;dr:
Technical limitations aside, there are very solid user experience reasons why this probably isn't allowed.
No, Windows will not let you set UI scaling below 100%.
(even if a stable workaround were to be discovered, most users would probably be quite unhappy with the results)
While I would love¹ to be proven incorrect, the implications of scaling at less than 100% are so fraught that this limitation is unlikely to change in the near future.
Background:
This has been the case for ages, likely since Windows first introduced the feature.
Compatibility with current software
The only ~purely technical~ reason I can think of:
The 100% scaling size likely uses the smallest base image (e.g. Explorer and Taskbar icons, mouse and text cursors) resources included in various existing Microsoft and 3rd-party applications.
User experience
Going below the 100% point may cause small UI text and icons, especially in application toolbars and the Taskbar to be blurred to the point of ambiguity.
Those fine lines in the taskbar 'Windows' menu icon? Blurred or gone.
Taken to the extreme, the UI ~might~ become so unreadable that the user is effectively prevented from being able to read the text even in the 'Settings' window and therefore is 'stuck': i.e. not able to navigate through 'Settings' to restore the original '100%' scaling mode.
(Luckily, Windows is never used to run any SCADA software where confusing two icons could theoretically cost money or lives.)
Performance:
Since those carefully-designed graphic assets don't exist, if sub-100% scaling were allowed, it would also likely cause extra CPU/GPU workload - that is why only certain fixed sizes of up-sampling are shown on the normal Display settings screen and why the Advanced scaling settings screen warns that custom scaling between 100-500% is "not recommended".
That might also apply to any fixed scaling option offered below 100%, and absolutely would for custom scaling sizes.
Some people enjoy reading:
Vector-based TrueType/OpenType fonts usually contain a ~lot~ of manual tweaking / hints to enable readable display of very small point sizes.
The marketing department & friends of the C-suite
Could they implement this at a limited range of options? 90%? 75%?
Perhaps - but it's extra testing for a horrible-looking edge case.
The existence of the option, even if only available as a registry hack, might cause some people to actually use it in kiosks and other public-facing displays; this risks the same sort of bad PR as when a BSOD is seen on the 'arrivals' screen at a train station or airport monitor.
Combined with the first example below, even a 90% option could cause trouble in some environments.
Example and tutorial:
Imagine how Windows might look displayed on one of those cheapo '1080p-supported' projectors that actually only contains an imager with a native pixel resolution of, say, 1024x576 (or even 480x234).
Windows thinks it can send 1080p, since that what the HDMI connection advertises, so it does: any text / vector content looks atrocious.
(At least in this case the user could normally² unplug the projector and reconnect to a normal monitor to restore functionality.)
See for yourself... while connected to any monitor (at that monitor's native resolution), with Windows set to 100% scaling:
Open Windows Notepad
Type or paste in any block of text
Now, use the Zoom Out command from the View menu³ five or more times in a row
While not an exact analogue, you may still see how hard it could be to read down-sampled text, even when very high-contrast (the best-case scenario).
¹: As someone currently typing this very answer on a 1080p connection to a 55" 4K television as a second monitor, I came across the question very much hoping this was possible. Sadly, logic intervened and killed my potential joy.
²: Unless the computer is actually stored somewhere locked or inaccessible, such as a NUC-style PC hidden above the false ceiling in a conference room.
³: Alternatively, press <CTRL>-<Minus> five or more times.
Given a rectangle that represents an area on a Windows screen that contains text, what is the best way to extract the text?
I know that it is possible using OCR, but even after significant pre processing, the quality is really poor.
Getting the Window Text using Win32 API does not always work as well.
Assuming that the text was rendered using a font, is it possible to get it from there?
Any directions would be extremely helpful. Thanks!
Given a rectangle that represents an area on window screen, the best way to extract text is indeed OCR. Use a better OCR library like this one from Microsoft.
The reason getting the window text using Win32 API does not work well is because there may be multiple windows in that rectangle. You will have to find out what all windows the rectangle contains and send a message to get the text for each window. It is not impossible but difficult to do and even if you manage to do that, you will run into issues of text alignment, etc. OCR is your best option.
It does seem possible without using OCR, as NirSoft SysExporter can do this:
https://www.nirsoft.net/utils/sysexp.html
This may be suitable for programmatic use as it can be run from a command line:
Starting from version 1.70, you can export the content of Windows
control from command-line, without displaying any user interface.
You may not be able to target it at a specific rectangle on the screen, but maybe the same result could be achieved by first scraping everything followed by some post-processing.
Further basic info:
SysExporter utility allows you to grab the data stored in standard
list-views, tree-views, list boxes, combo boxes, text-boxes, and
WebBrowser/HTML controls from almost any application running on your
system, and export it to text, HTML or XML file.
...
Known Limitations
SysExporter can export data from most combo boxes, list boxes,
tree-view, and list-view controls, but not from all of them. There are
some applications that use these controls to display data, but the
data itself is not actually stored in the control, but in another
location in the computer's memory. In such cases, SysExporter won't be
able to export the data.
Personally I've used it to grab text from what look like label controls.
I would like to loop through a sequence of images. I have tried using a Pivot control, but I don't like the blank space in between image transitions. I would prefer to use something that will animate between images smoothly. I also looked at the LoopingSelector control, but I can't seem to set the orientation to horizontal.
I'm assuming you're interested in a kind of image viewer like iOS offers, swiping right or left to navigate through the photos. If that's the case, I hate to say it but i think you're looking at building your own control.
I think to implement it properly these are the essential things you need to think about and address:
For performance' sake, load all the images you have into memorystream objects and store the binary data (you can get creative with this and only store the first 10-15 images, depending on how large the images are, doing this would enable your control to support thousands of images and still perform like a champ).
Once an image is about to be on-screen set the source of the image to the saved memorystream object that has the bytes loaded into it (this will minimize the work that the UI thread does, keeping the control performant and responsive)
Use Manipulation events to track the delta x of the motion someone uses when swiping left to right in order to actually perform the moving of the items
Move the images by changing their Canvas.Left property (you can go negative I think, otherwise just make your canvas the width of all the images you have combined)
Look up some of the available libraries to support momentum so you can have a natural smooth transition between images
I need to develop a desktop application which will
1.) have a list of the Different Application logos (Background Transparent) e.g. IE, FIREFOX, CHROME, PHOTOSHOP ETC.
2.) User will take a screenshot of desktop and save the image.
3.) Now my application need to search all the logos in the screenshot image and tell which all logos are present and where.
4.) I used OPENCV, it's working, but when user changes the desktop background & captures screenshot, it's not working as the transparent area of logo is getting the desktop background content.
Can somebody provide a solution or libraries open source, commercial to do this job.
This is easy to do using cross-correlation.
See my answer to this question.
Basically:
Start with desktop image and one template image for each icon
Apply edge detection (e.g. Sobel) to the desktop image and template images.
Throw away the original desktop image and templates, you won't need them anymore cause we'll be using the edge-detected images
For each template
Do template matching as you normally would
Threshold the maximum of the result. If it's above the threshold, you have a match at that position. Otherwise, no match.
If your icons are aligned in a grid on the desktop, you may be able to speed up your processing by only checking those specific grid positions.
EDIT
You can also save a lot of time by knowing which icons to search for. If you have access to the file system, then just look for *.lnk files (or any other extensions you may be interested in) in the directory that corresponds to the desktop (can't remember exactly what it is, but for Windows7 it's something like c:\users\misha\desktop). That will tell you what icons are there on the desktop. This will allow you to shorten your template candidate list before you go and do the template matching.
I like misha's answer and I think it should work for you. But it that doesn't work you could try replacing the transparant pixels in your reference logo with uniformly distributed random noise before trying the match. This will make the transparant pixels irrelevant for any matching computation because they will match just as bad no matter what there is on the desktop in those pixels.
I'm not familiar with the tools you're using, but I'm guessing you have to either:
a) Tell your program to ignore transparent pixels in the icon images during the comparison operation.
OR
b) Tell your program to treat transparent pixels in the icon images as "wildcards" which can be any color.
I would like to write a program that can mirror a portion of the main display into a new window. Ideally this new window could then be displayed on an external monitor. I have seen this uiltity for a flightsim that does this on a pc (a multifunction display extractor).
CLick here for a screenshot of the program (MFD Extractor)
This would be a live window ie. constantaly updated video display not just a static graphic.
I have looked at screen magnifiers or vnc clients for ideas but I think I need to write something from scratch. I have tried to do some reading on osx programing but where do I start in terms of gaining access to the display? I somehow need to extract the graphics from a particular program. Is it best to go near the final output stage (the individual pixels sent to the display) or somewhere nearer the window management stage.
Any ideas or pointers would be much appreciated. I just need somewhere to start from.
Regards,
There are a few ways to do this:
Quartz Display Services will let you get access to the video memory for a screen.
Quartz Window Services (a.k.a. CGWindow) will let you create an image of everything that lies below a window. If you create a borderless, transparent, empty, high-level window whose frame occupies an entire screen, everything below it will be everything on that screen. (Of course, you could create a smaller window in order to copy a section of the screen.)
There's also a way to do it using OpenGL that I never fully understood. That technique is demonstrated by a couple of code samples, OpenGLScreenSnapshot and OpenGLCaptureToMovie. It's more or less obsoleted by CGWindow, though.
Each of those will get you an image that you can then show or write to a file or something.
To show an image, use NSImageView or IKImageView. If you want to magnify it, IKImageView has a zoomFactor property, but if you want nearest-neighbor scaling (like Pixie, DigitalColor Meter, or xScope), I think you'll need to write a custom view for that (but even that isn't all that hard).