How to Replace a Color with Transparent

[engineerbill]

This may be a silly question, but I'm a new user. I have a Windows BMP file that contains only a 4-bit color pallette. I'd like to replace black with transparent but can't figure out how to do it. The "enable transparency" checkbox under "edit color pallette" makes it tantalizing but I just don't get it. Help!

[XnTriq]

Welcome to the forum, engineerbill

1. Go to View » Display Colour Information
   » The mouse cursor turns into an eyedropper with a tooltip next to it.
2. Move the color picker over the area of the image that you want to become transparent
   and remember the index number of the color beneath the cursor.
3. Go to File » Export.
4. Go to the tab for the format you want your image to be saved in.
   (For 4-bit indexed images, that would be GIF or PNG.)
5. Click on the Set transparency color... button
   and select the color with the index number you identified earlier.
6. Save the image.

[tomilipin]

Hi,
I have a very similar problem, so I'm posting a reply here - I followed your instruction, XnTriq, but the Set transparency color button is inactive when the Color mode is set to 16m. I have to choose literally any other Color mode to enable the Set transparency color button, but then the image quality is visibly worse.

Converting image from its original True Color to 32 bits doesn't help. Actually, it makes things even worse as the file size increases from 45 MB to over 60 MB.

I'm working on a TIFF file with transparent background, which shows correctly in Windows 7 generic image viewer, but in XnView the background is white - no idea why...

I'm using XnView 2.48, Windows 7. Please help

inactivebutton.png

[XnTriq]

I have a very similar problem, so I'm posting a reply here - I followed your instruction, XnTriq, but the Set transparency color button is inactive when the Color mode is set to 16m. I have to choose literally any other Color mode to enable the Set transparency color button, but then the image quality is visibly worse.

Converting image from its original True Color to 32 bits doesn't help. Actually, it makes things even worse as the file size increases from 45 MB to over 60 MB.

Unfortunately I don't have a short answer for you as there are many different types of transparency.

• XnView Forum
  • How to set PNG transparency color?
  • Free Adobe Photoshop Plug-Ins
  • How do I save a png with transparent background
  • Fails to detect 32 bit depth
  • Editing an images loses its transparency
  • Cant change background image completely
  • PNG transparency not preserved after conversion
  • Way to produce a transparent canvas?
  • Batch convert to transparency?
• Elsewhere
  • Patrick Hansen: PNG 8, 24, 32…what?
  • Jesse O'Chapo: Developers Guide to Images
  • Dave Hogue: What Are Index and Alpha Transparency?

I'm working on a TIFF file with transparent background, which shows correctly in Windows 7 generic image viewer, but in XnView the background is white - no idea why...

Could you upload the TIFF file to a hosting service so we can take a look?

[tomilipin]

Hi,
I'm slowly starting to accept the white background - it doesn't ruin my project.

Anyway, here's the file: http://wikisend.com/download/927280/Zywiec.tif

[XnTriq]

Anyway, here's the file: http://wikisend.com/download/927280/Zywiec.tif

Thank you for providing a sample, tomilipin. I've filed a bug report: Transparency is lost during conversion from CMYK to RGB

[tomilipin]

Oh, so it's a bug... Well, in that case I'm glad I could help by unintentionally finding it
Thanks!