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Thread: Need Alpha Channel Support in PNG images

  1. #21
    Moderator Enterprise User Bhikkhu Pesala's Avatar
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    I think the answer is don't hold your breath while waiting for this, as its a limitation of the Device Independent Bitmap that IrfanView uses.

    The advice I always give is that IrfanView is an image viewer, not an image editor. For any serious image editing, use a program that was designed for that task. IrfanView is fine for basic tasks, and one can do even more with IrfanPaint, but at heart it is just is a file viewer.
    Last edited by Bhikkhu Pesala; 17.06.2016 at 06:55 AM.

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    Professional User Mij's Avatar
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    Quote Originally Posted by ChrisA2107 View Post
    Have been trying to resize some PNGs with an alpha channel, only to find out it loses the alpha channel.

    A quick look in google and I found this thread from 2 years ago raising this issue. Is this something that is going to be resolved in IrfanView?
    Irfanview has never supported 32 bpp files with a transparency channel and I rather doubt that it is going to do so in the foreseeable future.

    The only form of transparency that is supported is for paletted images (256 colors or less) where one of the colors in the palette is specified as being the transparent color. AFAIK resizing a paletted image (256 colors or less) without changing the aspect ratio does preserve the palette so that you can still specify the original (or another) color for transparency when you save again. Resampling or stretching the image always results in a 24 bpp image, making it impossible to save the transparent color again. Other features and effects in Irfanview do that too.

    It is hard to make out exactly what is being requested here.

  3. #23
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    Lightbulb Full support PNG+ICO transparency/alpha channel

    Hi,
    it would be excellent add (long, long) missing full transparency / alpha channel support for PNG and ICO. The current version of IrfanView (4.42), support it only partially. Alpha channel (i.e.: 50% transparency), even if original image contain this, can not be saved!

    Details:
    Save dialog allows select only single color (through color picker or setting: Option-Properties-Viewing-Main window color) for transparency, or remove transparency/alpha channel. Is not available preserve original image alpha/transparency (currently this function not allowed).

    Thanks!
    Last edited by Bhikkhu Pesala; 17.06.2016 at 06:58 AM.

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    Moderator Enterprise User Bhikkhu Pesala's Avatar
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    This is a frequently requested feature so I have merged it with previous threads. However, for the reasons stated above it has not yet been implemented. I don't see it happening any time soon either. I suggest using the “ Open in external editor” option to edit PNG files with transparency.

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    Thank You,
    but this is very, very sad message . IrfanView is very good viewer , but unfortunately built on outdated(?) code and principles (without alpha). First request this problem - 9 year ago!!! Compatibility with Windows 95 is commendable (however this is 21 year old OS), but ignoring "modern" technologies (complex solving most ahead challenges) is unsustainable into future (especially in the software industry)!

    Jasc Paint Shop Pro 8 (2003) working with alpha and is still usable and I prefer it although there are newer Corel versions, I prefer it and I use it rather than Photoshop CS6. The usability is therefore, that is still compatible (later Corel version had some problems with Vista, W7, W8/8.1 W10), but the basic premise has not changed.

    Alpha / transparency is absolutely essential principle which can hardly replace with a similar function.

    By IrfanView in basic with alpha images I not expect advanced features as color correction, separate creating / edition alpha, but if you can save PNG, ICO... It should also support transparency . Or refuse crop, resize, color correction, etc. on the images with alpha without BIG NOTICE, that transparency will be removed.

    Working with Alpha channel is a function, that many, many years missing in IrfanView. If IrfanView missing some special format this is a less problem, than the lack of basic principle. Missing format / functionality can solve with plug-in, but if main program not support alpha, solutions throught plug-in will be difficult (or impossible). And more time in these state only worsens this situation...

    Thanks!

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    Moderator Enterprise User Bhikkhu Pesala's Avatar
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    I reminded Irfan Skiljan of this long-standing request. This is his reply:

    To change ALL image functions to work with layers (at least alpha layer) is a VERY big change => later.
    (some older plugins also work with max. 24 BPP, they can't be updated)
    Set up external editors for working with 32-bit PNG images.

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    Thank You,
    I wish whether it will succeed in the future...

    But I use Irfanview also for quick format conversion, if external editor does not support it (or many editors need) - i.e. convert to ICO. ICO not handle Paint Shop Pro, Photoshop (without plug-in), Corel Photo-Paint (only read - and very bad support)...

    In the first phase - these native conversion functions (without plug-ins) would be (mybe?) programmed without use IrfanView display core (bypass core, direct read and write files - without display it!). Internal conversion functions IrfanView (with alpha) should natively support PNG, ICO, TGA (maybe DDS).

    For ICO (DDS) format would be great if IrfanView could encourage full support for save each page (these multipage format) individualy/independently.

    Good luck!

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    Toxman, I think what you are asking for is never going to happen. The "display core" of Irfanview is the Windows Device Independent Bitmap (DIB) and the version that Irfan uses has a maximum of 24 bits per pixel. 32 bit versions of DIB do exist but, as I recall, it was Adobe who introduced them, not Microsoft and it is somewhere that Irfan is clearly reluctant to go.

    All the different supported input file formats are converted either with native code or plugins into a (max.24BPP) DIB when being loaded and are similarly converted from there back into any of the supported output formats when being Saved.
    That is why when a 32 BPP PNG, or other format with an alpha channel are being loaded, the required transparency effect of the alpha channel has to be applied to the RGB ones before they become a 24BPP DIB. If you want an Alpha channel in the output format, that also has to be created from somewhere when the file is saved.

    I too have a number of programs that I could use as an external editor to handle PNG files with alpha but since I use those programs infrequently I have to spend a long time re-learning how to use them every time I do. I would much rather be able to use Irfanview with which I am more familiar and could do the job quicker even if it did involve a lot more steps.

    Since the Insert overlay/watermark image feature was introduced a few versions back I can now apply a PNG to a background image and use the alpha channel to show the background image through the transparency of the PNG. That was a major step forward for Irfanview. I still cannot do what you want to do though, convert between different image formats with alpha layers, or edit the image while it is in the DIB format using the standard editing tools that Irfanview provides.

    After Loading a PNG with alpha (onto a plain background colour) I can use Image >View channel >Alpha to save the Alpha layer as a greyscale image file. I cannot though open the RGB content without the alpha transparency being applied and, even if I could, there is also no way that I can insert my Saved alpha channel back into the file when I subsequently save the RGB again.

    So those are the two features that I might choose to ask from Irfan and think I would stand a considerately better chance of getting them than for what you ask.

  9. #29
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    Hello Mij, thank You for answer. I just wanted to explain, what (me) most lacking in IrfanView. I understand that the problem is in the 24-bit DIB and what you write is interesting. I personally would not distinguish whether a 32-bit format introduced Microsoft, Adobe or anyone else. I think that neither of these companies have patent on an absolute smart. Even I would Microsoft suspect, they had not thought completely consequences. I infer this from fact, that many MS formats seem somewhat poorly thought out. If it was me decission, I would rather focus on useful technology that is useful globally (and I would be ignoring this long time ago forgotten Microsoft / Adobe war). Of course, I do not want anybody to assign this as work tasks!

    I am rather thinking aloud, how cleverly solve this. Me personally does not (so many) matter, that IrfanView not display true 32bit images - ideally with transparency to Windows Desktop... (although IrfanView is primarily viewer) . This does not affect the original file, but save / conversion function may affect this or any other files. IrfanView with good converison function would be an excellent universal bridge between programs!

    While not too many formats with conventional (alpha) transparent - first smart PNG, simply TGA, multipage ICO (based on BMP and PNG, ICO derivate? - ANI) and DDS (many compression algorithm).

    What You write (load / save alpha?), is certainly good idea for layered image viewing, but unfortunately I suspect, it does not solves the problem of saving(or yes?). Save saving may probably only full 32-bit support (may cause incompatibility of many parts and plugins) or lightweight bypass converter which do not use present internal 24 bit DIB (or any other 24 bit) format. I am not sure(!?), whether it would be simply possible replace or injecting alpha chanell into 32 or 24 bit image without open it first into internal format (and open it as 24bit is an endless circle). Save this alpha directly into many native formats is may be not easier, than creating a lightweight converter (maybe yes or maby not).


    If it is easier resolvable extraction and injection into the alpha channel 32 bit images (or expanding 24 bit images) - why not?!

    (Sorry for my bad English.)
    Last edited by toxman; 23.06.2016 at 03:24 PM.

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