uiimage introduces artifacts? How to fix?

I am building an application using App Designer and I am using images (Type = 'uiimage') and using the ImageSource property to display data. I am seeing artifacts on the GUI that are not in my data.

I can also produce the same behavior with a plain uiimage from the console.

img = ones(160, 160, 3, 'uint8') * 128;
img([48, 65], 1:4:end, :) = 0;
img([48, 65], 2:4:end, :) = 0;

fig = uifigure;
im = uiimage(fig);
im.ImageSource = img;
im.Position = [ 100, 100, 160, 160];
im.ScaleMethod = 'none';

The result from this is shown here:

Looking closely at the dashed lines shows the artifacts:

These look to me like jpeg artifacts. I am using ScaleMethod 'none' to try to rule out any resampling effects. In my application I am using a fixed size image that exactly matches the data size so it should not be performing scaling.

One of the purposes of my application is for users to closely scrutinize an image to look for artifacts in the underlying data, so it is important that the MxNx3 uint8 array is faithfully produced on the screen.

A "regular" figure with imshow does not show artifacts:

fig2 = figure;
imshow(img);

What's the best way to show the image in my application without artifacts?

[Nitin Kapgate]

I tried to reproduce the issue at my end using the above code, but I didn't find any artifacts in the image displayed using uiimage (verified in R2020a version of MATLAB)

Are you still facing this issue? Could you let me know your MATLAB version?

[Jamie]

Thank you, I am using 2019a. I can try 2020a and see if this has already been fixed. I'll report back what I find.

[Jamie]

I have installed Matlab 2020b and I am seeing the same artifact with uifigure + uiimage.

This is the result from my 'ver' command:

-----------------------------------------------------------------------------------------------------
MATLAB Version: 9.9.0.1570001 (R2020b) Update 4
MATLAB License Number: #######
Operating System: Microsoft Windows 10 Enterprise Version 10.0 (Build 19042)
Java Version: Java 1.8.0_202-b08 with Oracle Corporation Java HotSpot(TM) 64-Bit Server VM mixed mode
-----------------------------------------------------------------------------------------------------
MATLAB                                                Version 9.9         (R2020b)
Image Processing Toolbox                              Version 11.2        (R2020b)
MATLAB Compiler                                       Version 8.1         (R2020b)
Parallel Computing Toolbox                            Version 7.3         (R2020b)
Signal Processing Toolbox                             Version 8.5         (R2020b)

Also I notice your display says "Figure 1" with a toolbar. I would reemphasize that a regular figure + imshow works fine, and only the uifigure + uiimage has the issue.

You said you used uiimage, and I thought perhaps a regular figure + uiimage might be informative but apparently they do not work together.

Answer 1

[Nitin Kapgate]

Thank you @Jamie for bringing the issue of artifacts in the uifigure + uiimage workflow to my attention.

After revisiting the issue again, I could see artifacts being displayed when the image is displayed using the uifigure + uiimage workflow.

I have brought this issue to the concerned people and the issue might be resolved in future releases.

[Jamie]

Thank you.

[Nitin Kapgate]

As a workaround, you can serve cdata as file:

imwrite(img, 'imgFile.png');
im.ImageSource = 'imgFile.png'