Info

此问题已关闭。请重新打开它进行编辑或回答。

Any way to preserve the native resolution of data when saving a figure?

1 次查看（过去 30 天）

JDC 2017-10-12

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/360966-any-way-to-preserve-the-native-resolution-of-data-when-saving-a-figure

关闭： Rena Berman 2019-12-12

I've seen many ideas about changing paper size and the adjusting "-r" parameter, but it appears that all this does is take the on-screen displayed resolution and reproduce that at finer resolution. It doesn't get to the issue of saving a figure, whose data resolution is, say 1800x3200, to an image format that preserves that resolution on zoom. Is there any way to force MATLAB to save the figure as an image that would preserve that native high resolution - the way the .fig file would?

17 个评论
显示 15更早的评论隐藏 15更早的评论

JDC 2017-11-14

编辑：JDC 2017-11-14

Wrong. It was clearly presented several weeks ago until I had to deal with people, such as yourself, injecting opinions without understanding the problem. Here's some great advice often mis-credited to Einstein: Given an hour to solve a problem, use 55 minutes to understand the problem and 5 minutes to solve it. The rush to jump on a solution and not understand the clearly written words caused a cascade of braggadocio and ridiculousness, not at all unlike this thread, that obfuscated the original intent. The problem is one of context and very few people stop to understand the actual written word and fill in their own understanding. Words like data, resolution, images ... they mean different things to different people. People aren't mistaken because of missing information but rather assumed information. What went missing was the fact that it was clear the thread had been hijacked by people who were not thinking about the problem but rather quickly throwing out solutions in an effort, I suspect, to get some brownie points. Now, if you're quite done, it seems the problem was correctly understood by Cam even though it is still not correctly understood by others. So if it were clearly defined now as you indicate, everyone should now be able to understand it ... yet inexplicably, there is still confusion among some of us. Indeed, the very same people who cried "I don't understand" are STILL crying "I don't understand". Chew on that for a couple hours before you respond.

JDC 2017-11-15

编辑：Walter Roberson 2017-11-15

First, let's make sure everyone knows what we're dealing with. Before your HEAVILY edited reply above, it looked like this --------- There is nothing wrong with "I don't understand". I still do not find a clear statement, which defines uniquely what you want. I wrote:

I'm still convinced that the problem can be solved easily, as soon as it is exactly defined, what you want.

Instead of wasting time with the discussion, that this is an opinion, it would be more useful, if you write an exact definition of your need. Try it in one sentence, such that even I can understand it. Perhaps:

When I have an 7000x7000 image and display it in a figure, how can I save it as a raster image with 7000x7000 pixels?

The tedious discussion in this thread is caused by the fact, that such an explanation is missing. If you cannot explain clearly, what you want, do not blame me for asking questions for clarifications.

If such a clear definition is given, I can or cannot convert my opinion to code. In this thread you have insisted a long time on not giving a clear definition, because you had the opinion (!) that there is no solution. This is in ... ---------

Now, some definitions. A figure is a MATLAB object file. It contains the data and a significant amount of other parameters like the boundary and axes information. Lots of child fields. I'd like to assume you know this but it sounds like you are conflating the issue of a figure (a .fig file) and an image (a matrix of data). Now, here's the really important one - resolution. Resolution is the ability to determine the difference between two objects closely positioned in space. So a two by two matrix (image) say a blue pixel, a red pixel, a green pixel and a yellow pixel is not more resolved if each of those pixels is now represented by 100 pixels, making the new image 200x200. That's not higher resolution. It's redundant information and does nothing to resolve the underlying data. What you keep suggesting is to take an image as displayed on the screen and saving that "figure" as an "image" at higher "resolution". I'll say it one last time, MATLAB is constrained by what it can display on window device by the operating system. Maybe you know about device contexts (DCs) maybe you don't, but a DC is a significant component in displaying an image on a screen for any operating system (Windows, OSX, Linux, whatever). Matlab will NOT, indeed clearly CANNOT, take the data associated with the figure file and display it on a screen that has fewer pixels than it has data points. So, if you have a 7000x7000 data matrix you wish to display as a figure, you can, but it will be grossly undersampled. But the figure file has the data so you can zoom in on the data right down to the pixel. You cannot create an arbitrarily large print object to map your underlying data from a .fig file to an image file (like a png or bmp or yes, even a vector graphics file type like eps or svg) that preserves that 7000x7000 matrix of data. The best you can do is display it on a large screen, so the operating system can create a large enough DC that can then display the data as pixels which you can then save as an image.

Now, you may not understand that but I'm telling you what you are claiming is incorrect. You provided no code that addresses this issue. I stated on day one that I'm VERY familiar with the print command. I stated specifically that I was familiar with -r parameter of this method. That should have given an indication that we are not dealing with a basic issue. You have been a hinderance and an unpleasant one at that. You post derogatory and backhanded comments then quickly edit them, likely understanding that what you've written was inappropriate but not until after the reply was sent.

Cam has correctly identified the issue. Read his response. If you don't like it, tough. If you'd like to educate yourself regarding this phenomenon, by all means, load a very large image into MATLAB. A real image, not a random matrix as you'd have no way to observe the lack of coherence since, by definition, the two random matrices - the saved one and the original - are incoherent. Something significantly larger than your screen size - like this http://effigis.com/wp-content/uploads/2015/02/Airbus_Pleiades_50cm_8bit_RGB_Yogyakarta.jpg. Verify that you can zoom in on the "figure" right down to the pixel. Then zoom back out. Now, save that figure as an image anyway you like to preserve as much data as you can. When you now display that "image" in MATLAB as a "figure" you will discover that you cannot zoom down to the pixel. It will be block processed - meaning all your extra resolution did was over resolve the under resolved figure.

Now, I'm at the end of my patience. I've been using MATLAB for over 20 years and very nearly always find a way around a problem or identify a limitation in MATLAB itself. This is a limitation, since I can preserve more "resolution" from a "figure" on a larger screen than I can the same data on a smaller screen using the exact same parameters.

I can promise you one thing - I regret ever coming to this forum.

JDC 2017-11-15

Yet you keep coming back to continue to "edit" your responses. Yes, that's much more polite. And clever too, since the forum doesn't get to see your original less-than-polite responses. So I hope you are in fact done since there are people who have to go back to solving problems with rigor and understanding.

Rena Berman 2019-12-12

(Answers Dev) Restored edit

此问题已关闭。

回答（1 个）

Cam Salzberger 2017-10-12

3
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/360966-any-way-to-preserve-the-native-resolution-of-data-when-saving-a-figure#answer_285465

Hello,

It's a little hard for me to understand what you are asking for. You want an image that, when you zoom in on it, it increases its resolution (so you don't see chunky pixels)?

In that case, it sounds like you're looking for vector format images. Any raster format (JPG, PNG, etc.) will have a fixed resolution. When you zoom in, a single data point (pixel) of the image will grow to fit multiple pixels on the screen. A vector format (EPS, PDF, etc.) stores data on the "objects" within the image, rather than the pixels themselves. Thus, when you zoom in on a line, it recalculates what the line should look like on-screen, and will display it smoothly.

See the print documentation page (specifically the section on Vector Graphics Files) for information on your options.

-Cam

25 个评论
显示 23更早的评论隐藏 23更早的评论

Cam Salzberger 2017-11-14

在 MATLAB Online 中打开

Alright, I think I understand now, and can reproduce it to a certain extent. You have a very large image that you would like to annotate with axes-based graphics objects, then convert back to an image file. I believe the underlying issue comes from the warning you see when you display the image:

Warning: Image is too big to fit on screen; displaying at 17%

When you go to save the image, getframe and File -> Save As will provide it at the screen resolution size. saveas will provide it at a fixed 150 dpi, and if you scale up the resolution in print, it will simply stretch the displayed pixels and make the resulting image choppy. Keeping the resolution at screen resolution and expanding the size of the image through the 'PaperPosition' property has similar results.

Windows itself will prevent any program from making its window size larger than screen size, so you can't simply change the figure's 'Position' property to be as big as you need. You may be able to get around that somewhat if you have multiple monitors though. Windows (I believe) limits the size of windows to the combined width of the displays, and the largest height of the displays. So you may be able to push that boundary on width somewhat. However, it's a workaround at best.

You could, potentially, display just part of the image at a time. Or display the whole thing, annotate, and play with the axes limits to only view part of the image at a time. Finally, use getframe on the axes, and concatenate the resulting images together in a final large image. It's not an ideal workflow, but it could get around the issue.

I will put in an enhancement request with the appropriate team, including your workflow and the limitations you are running into. Our development teams will look into potentially including a method to meet your workflow in a future release of MATLAB.

-Cam

Jan 2017-11-15

@Cam: Yes, WindowAPI.mex is simply a wrapper function to the Windows API function SetWindowPos(). This can be used e.g. to create a window, which covers 3 monitors to display a movie in the 25:9 format, e.g. using the VLC player.

Matlab's ResizeFcn limits the size of a figure to the current screen - to be exact, to the usable area without the taskbar. Therefore setting the position to [0,0,1,1] does not create a full screen view of the inner position, but the outer position is set to the screen size. Therefore WindowAPI.mex uses a flag, which hides the change of the window size, such that Matlab's ResizeFcn is not triggered.

While a huge figure can be created using this method, Matlab's PRINT fails with a Java error during trying to grab its contents. The figure's contents can be grabbed by the Windows API directly also. E.g. a screenshot of the OS using Ctrl-Print works for a multi-monitor setup - even for monitors which are not existing physically. But on one hand JDC is not interested in my assistance to solve his problem, obviously. On the other hand it seems like Matlab figures are not a convenient way to insert annotations in high-resolution images. Therefore I'd follow Walter's suggestion or use e.g. ImageMagick.

JDC 2017-11-15

Remember this just a few short hours ago "I'm not interested in participating in such an impolite discussion. Therefore I have removed my comments and the trial to solve or narrow down the problem with code." Yet, here you are AGAIN, and AGAIN, ... and AGAIN. Do you have some problem that prevents you from not mentioning me? You think this "But on one hand JDC is not interested in my assistance to solve his problem, obviously." is not spam? Are we living in alternate universes communicating through some wormhole because I'm starting to get that impression. Here, let me fix this for you:

While a huge figure can be created using this method, Matlab's PRINT fails with a Java error during trying to grab its contents. The figure's contents can be grabbed by the Windows API directly also. E.g. a screenshot of the OS using Ctrl-Print works for a multi-monitor setup - even for monitors which are not existing physically. It seems like Matlab figures are not a convenient way to insert annotations in high-resolution images. Therefore I'd follow Walter's suggestion or use e.g. ImageMagick.

You're welcome.

Jan 2017-11-16

编辑：Jan 2017-11-16

A newcomer drops into the forum, asks an unclear question and gets upset due to questions for clarifications. He accuses two long term high reputation users for "spamming" and "trolling" and tries to attack with off-topic insults, sarcasm and parody. Finally he announces to disturb threads of other users. There is no doubt, who acts like a troll here.

JDC, your excitement is not impressing and nobody will care about your personal opinions. Walter (mainly) and I have posted more than 45'000 answers in this forum with great success and we will proceed with our style of communication. I do not have to defend against you, how I try to help to solve a problem or what I write while talking with another user. You simply do not have the power to influence, what I write.

The customs in the forum will not be changed, because one user is not satisfied in his first thread. You can check, how this forum works, and decide for yourself if you want to participate productively - or not. this is your decision and I cannot influence it by asking some questions for clarifications.

JDC 2017-11-16

This is unclear. You need to try to explain this again. I can help you if you just make a one line statement of what you are trying to do. Have you tried adjusting the -r parameter?

This is not a meaningful task. Instead of "asks an unclear question" you should write "a question that is unclear". It does not help if the members of the forum agree with you, that there should be something, when they know, that there is one already.

Obviously you care, otherwise you'd stop posting. But you can't because you just can't get that darn print function to work. I know you said it would work but it just doesn't seem to be doing what you said it would do. Try saving at -r15000000, see if that helps.

JDC 2017-11-16

Also, why do you keep saying HE and HIS. Are you sexist and only allow males to use MATLAB?

此问题已关闭。

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by

Any way to preserve the native resolution of data when saving a figure?

17 个评论
显示 15更早的评论隐藏 15更早的评论

回答（1 个）

25 个评论
显示 23更早的评论隐藏 23更早的评论

另请参阅

标签

Community Treasure Hunt

Any way to preserve the native resolution of data when saving a figure?

17 个评论 显示 15更早的评论隐藏 15更早的评论

回答（1 个）

25 个评论 显示 23更早的评论隐藏 23更早的评论

另请参阅

标签

Community Treasure Hunt

17 个评论
显示 15更早的评论隐藏 15更早的评论

25 个评论
显示 23更早的评论隐藏 23更早的评论