Rotate tool in 2.10 blurring layers

[BertyCraitbgoe]

Has anyone else encountered an issue where rotating a layer in 2.10 (using Windows 7 if that helps) ends up blurring the layer quite significantly? Obviously this means that 2.10 is currently unusable for me unless I can find a fix, which is a shame because otherwise I think it's amazing.

Here's an example of what I mean, the only adjustment made on the far right and bottom text is rotate: 

[rich2005]

I can get a match to your image if I use linear interpolation in the rotate tool.

NoHalo interpolation gives a better result.

[BertyCraitbgoe]

Thanks so much for looking into that for me, it definitely gives a much better result (just tested it). Is some degradation in quality to be expected from using the rotate tool? It's just I've never noticed it before when using previous versions.

[rich2005]

Things change. In Gimp 2.8 I had Sinc(Lanczos3) set as default. Gone in Gimp 2.10 and replaced by

NoHalo method when you do not reduce the size much (rotate, shear or something)
LoHalo method: when you downscale an image thats less than a half of the original size

[Ofnuts]

(06-15-2018, 12:59 PM)BertyCraitbgoe Wrote: Thanks so much for looking into that for me, it definitely gives a much better result (just tested it). Is some degradation in quality to be expected from using the rotate tool? It's just I've never noticed it before when using previous versions.

All the transform tools (Except Move & Flip) have to interpolate pixels. This will always degrade the image (even if some interpolation algorithms are better than others). This is more visible on sharp edges of text and logos(*). Degradation is cumulative, if you chain several such transforms the final result can be blurry (which is one of the purposes of the new "Unified transform tool"; you can do all the transformation in one call, so there will be only one single interpolation). 

(*) Because the edges are made of anti-aliasing pixels. And the interpolation of the anti-aliasing pixels by a given transform doesn't produce exactly the anti-aliasing pixels for the tranrformed edge. This is also why, when working with text and logos, it is better to apply the tools to the *path* and then redraw/pain the logo/text using the transformed path.

[BertyCraitbgoe]

(06-15-2018, 08:50 PM)Ofnuts Wrote:

(06-15-2018, 12:59 PM)BertyCraitbgoe Wrote: Thanks so much for looking into that for me, it definitely gives a much better result (just tested it). Is some degradation in quality to be expected from using the rotate tool? It's just I've never noticed it before when using previous versions.

All the transform tools (Except Move & Flip) have to interpolate pixels. This will always degrade the image (even if some interpolation algorithms are better than others). This is more visible on sharp edges of text and logos(*). Degradation is cumulative, if you chain several such transforms the final result can be blurry (which is one of the purposes of the new "Unified transform tool"; you can do all the transformation in one call, so there will be only one single interpolation). 

(*) Because the edges are made of anti-aliasing pixels. And the interpolation of the anti-aliasing pixels by a given transform doesn't produce exactly the anti-aliasing pixels for the tranrformed edge. This is also why, when working with text and logos, it is better to apply the tools to the *path* and then redraw/pain the logo/text using the transformed path.

Thanks. I just used the text as an example to show it up, I was actually working on a photo when I first noticed it. It's good to know these things because now I can plan for them in advance to save losing quality in the long run. (I noticed that adding some slight sharpening from G'MIC helped counteract some of the ill effects, but I'd rather just minimise the degradation period.)

[jchamp225]

(06-15-2018, 05:44 PM)rich2005 Wrote: Things change. In Gimp 2.8 I had Sinc(Lanczos3) set as default. Gone in Gimp 2.10 and replaced by

NoHalo method when you do not reduce the size much (rotate, shear or something)
LoHalo method: when you downscale an image thats less than a half of the original size

I tried both of these but it does not work.
In fact it's made the blurriness worse.
Am I doing something wrong?

All I do is rotate an image and it blurs out of control each time. Until reading this thread I have never touched the rotate settings. Using NoHalo blurred it more than Cubic (default), and LoHalo was 10x worse blur.

[rich2005]

Use whatever is applicable to the type of image you are adjusting. Give some details of what you are doing. It does not work will never get you anywhere.

Very small images for example might be better with cubic or even linear. Pixel Art maybe None.

[jchamp225]

(07-21-2021, 10:15 AM)rich2005 Wrote: Use whatever is applicable to the type of image you are adjusting. Give some details of what you are doing. It does not work will never get you anywhere.

Very small images for example might be better with cubic or even linear. Pixel Art maybe None.

xcf file format
1310 x 1926 px
100% opacity

Each time I rotate a layer it becomes more blurred. The amount I rotate does not seem to affect how much it blurs.

I'm completely new to gimp. I don't know what I'm doing really.
The only time I altered the Rotate settings was to change the settings as suggested above.
 - Interpolation was changed from Cubic (the default) to NoHalo (which only made the blur worse when I rotate a layer) and then to LoHalo (which made the blur way way worse when I rotate the layer)
 - If I change back to Cubic it just as bad as it was originally.

Again, new to this, so I have no idea if there are any other details needed to understand the situation.

I have noticed that the same thing happened on a phone app I once used IbisPaint X, but I assumed it was due to it being a phone app.

All I know is everyone I ask tells me its some other thing that causes it, but so far nothing I have been told works.

[PixLab]

Is something like the image below good enough?
(I added a curve)