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Thread: Need help converting .bmp to .jpg in a certain way

  1. #1
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    Question Need help converting .bmp to .jpg in a certain way

    Hello,

    I basically ripped picture files from PC games, and the format comes out in .bmp.

    However, with .bmp, sometimes the pictures file have extra data that looks out of place. To fix this, all you do is convert the .bmp to .jpg or .png and that extra data on the picture will go away.

    However, when I convert using irfanView, it doesn't remove that extra data on the image. Any idea why? Or what I might be doing wrong?

    Thank you for your time.
    Last edited by Bhikkhu Pesala; 28.02.2020 at 05:16 PM.

  2. #2
    Moderator Enterprise User Bhikkhu Pesala's Avatar
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    Please attach a sample BMP, or a 7z archive of it if it is too big to attach.

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    So this is the what the picture looks like in .bmp format from the ripped pc files

    Click image for larger version. 

Name:	Capture.JPG 
Views:	15 
Size:	133.8 KB 
ID:	5758

    now, when I take that picture and convert it to .jpg using any random online .bmp to .jpg conversion, the results is below

    Click image for larger version. 

Name:	Capture2.JPG 
Views:	11 
Size:	100.2 KB 
ID:	5759

    Not entirely sure how this works to be honest, not sure how data can disappear from pictures like that.

    Anyway, I don't trust random websites. I trust irfanview. However, when I try using conversion to .jpg, the results looks the same as the original .bmp

    P.S., please note that the attached is just a snap shot of the original file, I didn't want to post it because I deemed it borderline inappropriate. I didn't want to post that since I am not sure what is the rules in-regards to adult pictures.

  4. #4
    Power User j7n's Avatar
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    You should have uploaded the original file so that the data format can be identified. The image most likely is 32-bit with an alpha channel, which indicates the degree of visibility for each pixel. Support for alpha transparency is inconsistent. There are multiple ways it can be represented in a program (mask, channel, premultiplied) and it is often not transferrable from one format to another.

    IrfanView does not support alpha for BMP. You could use Photoshop or PixelFormer to convert these pictures to another format, but neither have a batch mode. XnView is a similar program to IrfanView and supports this format, but I have little experience with it. For advanced automation from the command-line, look into ImageMagick.

    Maybe your tool can export into Targa, which is another format used with games, and the transparency better supported. IrfanView can read it, blend it against a background color, and lose the alpha upon saving. (You probably want to keep it for future use of the artwork.)
    Last edited by j7n; 28.02.2020 at 05:24 PM.

  5. #5
    Moderator Enterprise User Bhikkhu Pesala's Avatar
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    What you might be doing wrong is breaching the Game-maker's copyright, but I will leave you to decide on that.

    I think the reply from j7n should solve the issue for you, but if you want to upload the image in an archive that is OK. We can delete it later.

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