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    • CommentAuthormattekure
    • CommentTimeSep 16th 2018 edited
     
    I was having a discussion recently on exporting images from CC3+ and there were different ideas on how to produce the best final quality output. My standard procedure was to just export to JPG and set everything in the dialog such as resolution, antialias and jpg quality. Several other methods were suggested as possibly producing better quality output and I wanted to get everyones opinions on that. This is assuming no further editing of the map being done after its exported, just getting it to the right size/quality.

    Some of the alternatives suggested were:
    Export to a BMP/PNG first, then use software such as GIMP to convert to JPG.

    Export at a much higher resolution, then use GIMP to rescale it down.

    Export at a higher resolution without antialias and use GIMP to antialias and reduce to size.

    And other similar processes along those lines. The pattern of these suggestions seems to be that using some other image manipulation tool afterward will produce a superior result to the JPG produced directly by CC3. I havent been able to tell a difference, but I dont have a really critical, artistic eye. So what do you all think?

    EDIT for clarification:

    My question is specific to having the final image format being JPG. The final images will be used in a VTT that requires images be JPG, so I am trying to understand a process for producing the best looking JPG I can for that.
    • CommentAuthorWyvern
    • CommentTimeSep 16th 2018
     
    From purely personal experience, the better quality results are always PNG files. JPGs are great because they come out as significantly smaller files in terms of computer memory, so are easier to send to other people by, for instance, e-mail, or to display where file-size is a key constraint (such as on some online Forums). BMPs I've historically tended to avoid, as producing poor-quality images with HUGE file sizes.

    I'm not sure what advantages tinkering with the final image in GIMP or other image manipulation software might be if all you needed was the CC3+ map image. If you needed to add highlighting or non-map labels (for use in a tutorial, say), that might make sense. But converting any file to a JPG will reduce its final appearance quality overall, no matter what you do with it, so far as I understand it anyway.
    • CommentAuthormattekure
    • CommentTimeSep 16th 2018
     
    You bring up a good point I should have clarified. I understand that JPG files will always have some degradation. The files I am looking at need to be a JPG in the end as they will be used in a VTT that requires that format. So I am trying to see what method, either one I listed, or something else, will produce the best quality of JPG output.
    • CommentAuthorLoopysue
    • CommentTimeSep 16th 2018
     
    As Wyvern has already pointed out, unless you need to do some serious post processing (adding stuff in GIMP that you can't do anywhere near as easily in CC3, like detailed variable hill shading, or hand drawn highlights/shadows for individual focal points), its just a case of exporting it directly from CC3 as a JPEG with a reasonable amount of antialiasing. The default setting of 66% is a bit over the top in my opinion. I usually use about 20%

    If you are intending to do a lot of post processing, then export as a PNG about 2 x the desired end result, and work on it at that scale. Once you are finished with the post processing in GIMP, save the GIMP file (in case you change your mind about any of the things you touched up), export the finished map to a PNG, then reopen the PNG and scale it down to the desired size.
    • CommentAuthorWyvern
    • CommentTimeSep 16th 2018
     
    If you are stuck with needing a JPG, then I'd go with Sue's advice, using a straight CC3+ JPEG export, and experiment with different values for the antialiasing, making sure to set the JPEG quality level at 100%.
    • CommentAuthormattekure
    • CommentTimeSep 16th 2018
     
    Ok, so there isnt anything inherently superior about GIMPs ability to convert PNG to JPG? For example, if I take a file and export it to PNG, then convert it to a JPG at 100% quality. Will that produce a better result than just producing it as a JPG directly from CC3?

    Also, when you do export it to PNG at 2x the size to work on in GIMP, do you turn off anti-aliasing and only apply that during the GIMP export to JPG? Or do you still have the anti-aliasing on when exporting to PNG?
    • CommentAuthorLoopysue
    • CommentTimeSep 16th 2018
     
    In answer to your first question, no there isn't :)

    As a sub-answer to the same question, exporting a JPG at 100% quality will give you a file that is just as big (if not bigger than) a png file of the same image and size.

    In answer to the second question, brushes in GIMP operate in a way that is automatically antialiasing (unless you deliberately turn it off), so if you want your added hand drawn highlights and shadows to blend with the image from CC3, then I would use AA on export from CC3 so that you are drawing antialiased brush strokes on an antialiased background. Note that I would export from CC3 as png to avoid any loss of detail or compression artefacts before I've even begun drawing in GIMP.
    • CommentAuthorjslayton
    • CommentTimeSep 16th 2018
     
    Historically, it was possible to get better image quality at the end by exporting to higher resolution without antialiasing and using a program that did high-quality downsizing for the final result (e.g. GIMP). For the last couple of versions, however, antialiased exports from CC3+ use a BMP image as a temporary image and then use an external image processing system to do the downsizing and conversion to the final image size and format. The external image processing system is called ImageMagick and it provides results on-par (or better) with GIMP's resizing system. CC3+ uses BMP as its intermediate file format because BMP files are just raw rasters of pixels with a file header and so exactly match the internal processing formats in CC3+.

    If you're going to work on the image in an image editor after you export data from CC3+, antialiasing the export directly in CC3+ won't get you much. Exporting at a higher resolution, editing the data in your image editor at that resolution, and then resizing and saving your data into its final form will get you about the same quality as exporting antialiased from CC3+ and editing at the final resolution in an image editor, but it will require that you be much more careful about tiny details in the image editor because you don't have the downsampling to hide the high-frequency noise from shaky fingers (maybe that last part is just me).
    • CommentAuthormattekure
    • CommentTimeSep 16th 2018
     
    thanks everyone, it sounds like for what I need, going straight to JPG is best.