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 Computer Math and Games in Pascal (preview) Lazarus Handbook

Author Topic: [LazPaint] Layers: Loss of quality  (Read 3724 times)

AlexisBlessing

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[LazPaint] Layers: Loss of quality
« on: March 07, 2021, 06:13:24 pm »
Hello, I am new to the forum, my English is not very good, but I will do my best to communicating my problem to you all in your native language of preference and I hope you understand me correctly.

My problem and concern is the following: When rotating a layer (without deforming it) it loses quality in its image, it is somewhat scalable, so each time I decide to rotate that same layer, the quality is lost more and more and plus. This makes me waste a lot of time editing them, because I almost always have to redraw them to get the quality of the first stroke again. I would like to know if it is possible to configure LazPaint so as not to lose the quality of the layers when applying a rotation or displacement of it.

My all thanks in advance for this awesome app and my apologies for my bad English. I await your prompt replys.
« Last Edit: March 07, 2021, 06:19:06 pm by alexisblessing »

marcov

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Re: [LazPaint] Layers: Loss of quality
« Reply #1 on: March 07, 2021, 06:30:32 pm »
Do you rotate over an arbitrary angle, or 90,180,270 degrees?

AlexisBlessing

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Re: [LazPaint] Layers: Loss of quality
« Reply #2 on: March 07, 2021, 07:08:30 pm »
Do you rotate over an arbitrary angle, or 90,180,270 degrees?

Marcov, Thank you very much for your answer!

In general, the layer rotations I do are at arbitrary angles (they are very useful to me). Just now when reading your comment I was trying rotating a layer by pressing the "ctrl" key (I imagine it is the way to get the angles that you have named me before) and in the same way, image quality is lost, this being a bit arbitrary. On the other hand, I could notice that when moving a layer, its quality is also lost when it is positioned in very specific areas of the plane.
« Last Edit: March 07, 2021, 07:12:29 pm by alexisblessing »

AlexisBlessing

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Re: [LazPaint] Layers: Loss of quality
« Reply #3 on: March 07, 2021, 08:07:38 pm »
I attach a screenshot of the problem after several rotations and displacements of a layer compared to its original (the copy is at the same angle as the original). At first the loss of quality is minimal, but after several hours of work the loss of quality is very high.

circular

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Re: [LazPaint] Layers: Loss of quality
« Reply #4 on: March 07, 2021, 09:45:52 pm »
Hi alexisblessing

In order to preserve the quality, you need to be aware of rasterization.

Basically, when you draw a vectorial shape, you can rotate it any number of times, it will never loose quality.

If you draw with the pen tool, then it rasterizes the layer, so previous information is lost. So if you rotate it again, it will get a bit more blurry.

To make it simple, if you use raster tools (pen, brush, eraser, flood fill, distortion), then try to do it on a separate layer, in order to avoid rasterizing existing content. The only non lossy transformation you can do is to move the layer, flip it vertically and horizontally.

If you need to transform many times, use vector tools only (polygon tool, curve tool...). You can check anytime if what you do rasterize the layer by look at the icon near the layer. Vector layers have a circle and a triangle. Raster layers have a square with a grid.

Regards
Conscience is the debugger of the mind

AlexisBlessing

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• Posts: 5
Re: [LazPaint] Layers: Loss of quality
« Reply #5 on: March 08, 2021, 02:58:21 am »
Hi alexisblessing

In order to preserve the quality, you need to be aware of rasterization.

Basically, when you draw a vectorial shape, you can rotate it any number of times, it will never loose quality.

If you draw with the pen tool, then it rasterizes the layer, so previous information is lost. So if you rotate it again, it will get a bit more blurry.

To make it simple, if you use raster tools (pen, brush, eraser, flood fill, distortion), then try to do it on a separate layer, in order to avoid rasterizing existing content. The only non lossy transformation you can do is to move the layer, flip it vertically and horizontally.

If you need to transform many times, use vector tools only (polygon tool, curve tool...). You can check anytime if what you do rasterize the layer by look at the icon near the layer. Vector layers have a circle and a triangle. Raster layers have a square with a grid.

Regards

Hello Circular! Thank you very much for your answer!

Aaaaaah, perfect! Of course, I was not aware that I was working with vector elements and that these were rasterized when applying elements from non-vector tools. I have always used the curve tool a lot, which is the one that I have been having problems with when using the eraser tool when applying different touch-ups. If anything, how do I correctly remove a vector element? For example, I have to erase a line of one hundred vector lines and I would not like to have to create a layer for each of them, or in the case of needing to eliminate the first one, having to use a "ctrl + z" until reaching it .

On the other hand, I was thinking of creating another post for this question but it is very similar to this problem with the loss of image quality, in this case I am talking about the "selector tool". Selecting a fragment of an image and moving it around or rotating it, the selected fragment loses a lot of image quality. Taking into account that the culprit is also rasterization. Is it possible to convert a rasterized layer manually to a vector layer? (By converting all its internal elements to vectors).

Finally, I have noticed that in addition to the symbols that you named me in each layer, there is a symbol of a square with a rotation arrow, the latter, what would it be indicating to me? Is it a vector or raster layer? If it is not the same as any of the above, how is it different from the other two?

Beforehand thank you very much!

circular

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Re: [LazPaint] Layers: Loss of quality
« Reply #6 on: March 08, 2021, 07:15:01 pm »
Ok indeed if you use the eraser it will erase pixels and thus rasterize. To remove part of a vector curve, use the Edit shape tool. When the shape is selected, hover the point you want to delete and press the Delete key. You can also insert points with Insert.

The square with a rotation arrow is a raster layer that is transformed (rotated or zoomed). You can transform it any times you want without losing the original raster information. But if you start to paint on it, it will be rasterised with the transform, thus losing information.

When using the raster selection, I would suggest to move it to a new layer and paste it. The you can transform the layer any times you want while keeping the original pixels.

You’re welcome 😊
Conscience is the debugger of the mind

AlexisBlessing

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• Posts: 5
Re: [LazPaint] Layers: Loss of quality
« Reply #7 on: March 08, 2021, 09:30:56 pm »
Ok indeed if you use the eraser it will erase pixels and thus rasterize. To remove part of a vector curve, use the Edit shape tool. When the shape is selected, hover the point you want to delete and press the Delete key. You can also insert points with Insert.

The square with a rotation arrow is a raster layer that is transformed (rotated or zoomed). You can transform it any times you want without losing the original raster information. But if you start to paint on it, it will be rasterised with the transform, thus losing information.

When using the raster selection, I would suggest to move it to a new layer and paste it. The you can transform the layer any times you want while keeping the original pixels.

You’re welcome 😊

Hi Circular!

Great explanation and information! I understood everything correctly and tested everything successfully.

Again, very grateful for your time and for this fantastic app!

My warmest greetings from Buenos Aires, Argentina.

circular

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Re: [LazPaint] Layers: Loss of quality
« Reply #8 on: March 08, 2021, 11:02:49 pm »
I am happy all went well.

Glad you like the software
Conscience is the debugger of the mind