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    no bug Opening paint dialog affects image display quality

    Noticed this, admittedly very minor, bug. Opening the paint dialog, with an image displayed at more or less than 100%, causes the image anti-aliasing to be lost (ie the image goes all jaggy). Before and after example below:
    Click image for larger version

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    Using Win7 Home, Irfanview 4.44 32bit

    #2
    Probably not a bug. There is no problem if "Resample for zooming" is disabled, so all we can say is that the Paint plugin does not support anti-aliasing.
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      #3
      Originally posted by Bhikkhu Pesala View Post
      Probably not a bug. There is no problem if "Resample for zooming" is disabled, so all we can say is that the Paint plugin does not support anti-aliasing.
      That setting makes no difference to it

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        #4
        Originally posted by JDPower View Post
        That setting makes no difference to it
        It certainly does make a difference.

        Try saving your screen shots as PNG as JPG artefacts are distorting the results.
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          #5
          I think you've misunderstood the bug. It's nothing to do with any saved image, merely the one displayed in Irfanview. Opening the paint dialog causes the displayed image to appear 'aliased'/jagged.
          Last edited by Bhikkhu Pesala; 13.01.2017, 03:48 AM. Reason: Shouting removed.

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            #6
            This is a feature, not a bug. IV-Paint is for editing images. When I zoom in e.g. to 200% or more I want to see the pixels without any smoothing. Only this way I can edit precisely, such as painting in the background around the edge of an object using the brush or stamp tool.

            currently running 4.56 / 32 bit

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              #7
              Originally posted by jazzman View Post
              This is a feature, not a bug. IV-Paint is for editing images. When I zoom in e.g. to 200% or more I want to see the pixels without any smoothing. Only this way I can edit precisely, such as painting in the background around the edge of an object using the brush or stamp tool.
              Also missing the bug. I am well aware an image pixelises when zoomed, been editing images for a looong time. This is creating pixels that aren't in the image, whether the image is zoomed or shrunk. This actually makes pixel accurate editing worse as you're not seeing the pixels in the image, but pixels caused by Irfanview's bad rendering of the image.

              Just look at the example images in the first post - they are at the same zoom level, but the one with the paint dialog open has added pixelation that shouldn't be there.
              Last edited by Bhikkhu Pesala; 13.01.2017, 11:12 PM.

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                #8
                If you have been editing images for a looong time then it is high time you understood the difference between resizing and resampling images.
                What you are probably doing in your first post is comparing a resized image captured from the screen when the Paint plugin is open with a resampled one captured when the plugin is closed. It is only the way that the image is rendered on the screen that differs. If you had saved the file from the File menu rather than making screen captures the result would be the same whether the plugin was open or closed.

                To illustrate I drew a red straight line 1 pixel wide in Paint and then closed the plugin. I then made screen captures at various zoom levels with Resample turned on and then turned off. With "Use resample for fitting" turned off the display is Resized instead of Resampled when it is forced to fit the window again after the zoom ratio is changed. The results are shown below.

                In the first 2 images the zoom ratio has been set to 1200% (12 times the size it was drawn at) and a small section of the line captured. In both of course "pixels are created". In the resized display (1) there are 144 pixels, in a 12x12 block for each original pixel so you can see that that the original line was drawn in sections 1 pixel wide and either 2 or 3 pixels high to approximate as far as possible the slope of the line. In the resampled display (2) you can see that the line is blurred by adding other shades of red to disguise the jagged outline. In a drawing program you do not want to deliberately blur objects.

                The next 2 images are captured at a lower zoom ratio. As the zoom is reduced it becomes more and more difficult for the resize algorithm to produce a near square block of pixels for each pixel of the original and at some ratios the diversity of shapes makes the result appear very jagged. I chose 151% because that looked especially bad to me. Image (3) has an "alias pattern" that tricks the brain into thinking it is seeing something other than a smooth straight line. The blurring resample algorithm in (4) disguises the pattern and stops the brain from being deceived.

                Images (5) and (6) show the Irfanview Information dialog and you can see that the resized image still has only the 2 colors (red and white) of the original drawing whereas resample has created a palette of 256 shades.

                Click image for larger version

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                Click image for larger version

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Name:	1200% Resampled 256 color.png
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ID:	81562

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                  #9
                  Originally posted by Mij View Post
                  If you have been editing images for a looong time then it is high time you understood the difference between resizing and resampling images.
                  What you are probably doing in your first post is comparing a resized image captured from the screen when the Paint plugin is open with a resampled one captured when the plugin is closed. It is only the way that the image is rendered on the screen that differs. If you had saved the file from the File menu rather than making screen captures the result would be the same whether the plugin was open or closed.

                  To illustrate I drew a red straight line 1 pixel wide in Paint and then closed the plugin. I then made screen captures at various zoom levels with Resample turned on and then turned off. With "Use resample for fitting" turned off the display is Resized instead of Resampled when it is forced to fit the window again after the zoom ratio is changed. The results are shown below.

                  In the first 2 images the zoom ratio has been set to 1200% (12 times the size it was drawn at) and a small section of the line captured. In both of course "pixels are created". In the resized display (1) there are 144 pixels, in a 12x12 block for each original pixel so you can see that that the original line was drawn in sections 1 pixel wide and either 2 or 3 pixels high to approximate as far as possible the slope of the line. In the resampled display (2) you can see that the line is blurred by adding other shades of red to disguise the jagged outline. In a drawing program you do not want to deliberately blur objects.

                  The next 2 images are captured at a lower zoom ratio. As the zoom is reduced it becomes more and more difficult for the resize algorithm to produce a near square block of pixels for each pixel of the original and at some ratios the diversity of shapes makes the result appear very jagged. I chose 151% because that looked especially bad to me. Image (3) has an "alias pattern" that tricks the brain into thinking it is seeing something other than a smooth straight line. The blurring resample algorithm in (4) disguises the pattern and stops the brain from being deceived.

                  Images (5) and (6) show the Irfanview Information dialog and you can see that the resized image still has only the 2 colors (red and white) of the original drawing whereas resample has created a palette of 256 shades.

                  [ATTACH=CONFIG]4608[/ATTACH] [ATTACH=CONFIG]4613[/ATTACH] [ATTACH=CONFIG]4610[/ATTACH] [ATTACH=CONFIG]4612[/ATTACH]
                  [ATTACH=CONFIG]4611[/ATTACH] [ATTACH=CONFIG]4609[/ATTACH]
                  Thanks for that, did the same thing and now I'm following what's going on. It's not something I've ever noticed in Irfanview (admittedly I rarely use the paint dialog), and doesn't (noticeably) happen in the editors I do use (which presumably don't resample for zooming).

                  And thanks to googling your exact phrase "resample for fitting", I discovered not all Iview settings are in the settings menu (how intuitive), and the resample options are in the 'View' dropdown. So I wasn't going mad after all, reading through every settings page several times over trying to find it lol (I've only been using it for 10+ years!!! )

                  The pixels still seem to move slightly when opening the paint dialog for some reason, but done enough chasing and it's behaving how I expect/prefer now

                  So thanks Mij for being patient and pointing out what should have been obvious, and NON bug closed lol

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