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I made a calendar. I have .jpg texture that should be one page. enter image description here

I just painted it with various colours because this is what it looks like in rendered view.

enter image description here

While .png texture works fine enter image description here

The only thing I change in material setup is the image texture. Does anyone know what is happening here? It seems like blender has problems reading the .jpg or something.

EDIT: I did not post material setup, because it has nothing to with it 100%. Blender clearly has some issues with .png and .jpg formats. enter image description here

I continued on my project and I came across another problem. Now I have this image, which is .pngenter image description here

Material setup is THE SAME, just texture to diff shader. This is what it looks like in viewport. enter image description here

UVs are just faces covering the whole picture, like this: enter image description here

But render looks ok, so I have no idea what is happening, I can work around it obviously, but it's strange at least :). Render: enter image description here

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    $\begingroup$ Please add images of your node setup. $\endgroup$ Apr 19 '18 at 18:22
  • $\begingroup$ Please use the edit link at the bottom of your question (i.stack.imgur.com/lXFuK.png) and add more information. We don't know how you set up your project or your textures. $\endgroup$
    – user1853
    Apr 20 '18 at 1:45
  • $\begingroup$ did you save and Pack your painted images? Probably they are not loaded correctly. Try reloading your textures or restart blender. Also check that you selected the right texture for rendering $\endgroup$
    – HenrikD
    Apr 20 '18 at 8:05
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Unfortunately the original question did not contain enough information for a clear answer, but then, as it was compounded with second a totally unrelated matter, I will attempt to clarify the second.

The problem is how the image is created and the format used. Depending on the program used to create the image, there can be some extra information left on the RGB channels that should have not been part of the image in the first place. In other words, the alpha channel and the RGB information have not been associated. Saving as PNG only makes the problem persist, because it uses unassociated alpha.

If you look at the image in the UV/Image editor the alpha channel

You will can see the RGB information and you will notice that the image has those black bars, and some extra information that does not coincide with that of the alpha mask (6 extra elements on the bottom left of the image and some extra things on the bottom right as well).

enter image description here

The PNG file is using "unassociated" alpha, instead of "associated", where the pixels that are meant to be transparent would be multiplied by the alpha channel and should be black.

When you view the image in texture view, the information on the RGB channel is used. If you use any other view (material or render) the alpha channel will work correctly.

enter image description here

The proper way to deal with unassociated alpha is to multiply, the RGB with the alpha information.

enter image description here

Or to use it as a mask to mix the shader color or to mix different shaders.

enter image description here

enter image description here

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