Results 1 to 9 of 9

Thread: Opening paint dialog affects image display quality

  1. #1
    IV Amateur
    Join Date
    Sep 2012
    Posts
    10
    OS
    64-bit Win 7 Home Premium SP1

    Default 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. 

Name:	SS closed.jpg 
Views:	31 
Size:	112.0 KB 
ID:	4598Click image for larger version. 

Name:	SS open.jpg 
Views:	29 
Size:	134.9 KB 
ID:	4599

    Using Win7 Home, Irfanview 4.44 32bit

  2. #2
    Moderator Bhikkhu Pesala's Avatar
    Join Date
    May 2007
    Location
    East London
    Posts
    4,854
    Version
    IrfanView 4.44
    OS
    64-bit Win 10
    CPU Cores
    1

    Default

    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.

  3. #3
    IV Amateur
    Join Date
    Sep 2012
    Posts
    10
    OS
    64-bit Win 7 Home Premium SP1

    Default

    Quote 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

  4. #4
    Moderator Bhikkhu Pesala's Avatar
    Join Date
    May 2007
    Location
    East London
    Posts
    4,854
    Version
    IrfanView 4.44
    OS
    64-bit Win 10
    CPU Cores
    1

    Default

    Quote 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.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Resampled.png 
Views:	11 
Size:	233.4 KB 
ID:	4601   Click image for larger version. 

Name:	Not resampled with Paint Dialogue.png 
Views:	12 
Size:	15.8 KB 
ID:	4602  

  5. #5
    IV Amateur
    Join Date
    Sep 2012
    Posts
    10
    OS
    64-bit Win 7 Home Premium SP1

    Default

    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 at 03:48 AM. Reason: Shouting removed.

  6. #6
    Multiple User jazzman's Avatar
    Join Date
    Aug 2007
    Posts
    354
    Version
    IrfanView 4.42
    OS
    32-bit Win XP Home SP2
    CPU Cores
    2

    Default

    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.

  7. #7
    IV Amateur
    Join Date
    Sep 2012
    Posts
    10
    OS
    64-bit Win 7 Home Premium SP1

    Default

    Quote 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 at 11:12 PM.

  8. #8
    Professional User Mij's Avatar
    Join Date
    Mar 2007
    Location
    Camberley, Surrey, UK
    Posts
    2,520
    Version
    IrfanView 4.44
    OS
    32-bit Win 10
    CPU Cores
    3

    Default

    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. 

Name:	1200% resized.png 
Views:	15 
Size:	13.0 KB 
ID:	4608 Click image for larger version. 

Name:	1200% resampled.png 
Views:	17 
Size:	30.4 KB 
ID:	4613 Click image for larger version. 

Name:	151% resized.png 
Views:	15 
Size:	10.3 KB 
ID:	4610 Click image for larger version. 

Name:	151% resampled.png 
Views:	17 
Size:	15.6 KB 
ID:	4612
    Click image for larger version. 

Name:	1200% Resized 2 color.png 
Views:	18 
Size:	21.9 KB 
ID:	4611 Click image for larger version. 

Name:	1200% Resampled 256 color.png 
Views:	13 
Size:	40.6 KB 
ID:	4609

  9. #9
    IV Amateur
    Join Date
    Sep 2012
    Posts
    10
    OS
    64-bit Win 7 Home Premium SP1

    Default

    Quote 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.

    Click image for larger version. 

Name:	1200% resized.png 
Views:	15 
Size:	13.0 KB 
ID:	4608 Click image for larger version. 

Name:	1200% resampled.png 
Views:	17 
Size:	30.4 KB 
ID:	4613 Click image for larger version. 

Name:	151% resized.png 
Views:	15 
Size:	10.3 KB 
ID:	4610 Click image for larger version. 

Name:	151% resampled.png 
Views:	17 
Size:	15.6 KB 
ID:	4612
    Click image for larger version. 

Name:	1200% Resized 2 color.png 
Views:	18 
Size:	21.9 KB 
ID:	4611 Click image for larger version. 

Name:	1200% Resampled 256 color.png 
Views:	13 
Size:	40.6 KB 
ID:	4609
    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

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •