I have an image that I'm trying to pad some transparent border. But I get error:

"The specified padding value is not compatible with a 3-channel image."

data = Table[{45, 45, 45}, {20}, {25}];
p = Image[RawArray["Byte", data], "Byte", Rule[ColorSpace, Automatic],
    Rule[Interleaving, True]];

ImagePad[p, 10, Transparent]

What does this error mean and how to solve it?


If test on the documentation figure, padding transparent works even it has a Automatic color space:

enter image description here

  • $\begingroup$ Is there a reason, why you are using Automatic for the ColorSpace? $\endgroup$ – Karsten 7. Sep 6 '14 at 17:02

You have to convert Transparent into, e.g., the RGB color space:

ImagePad[p, 10, ColorConvert[Transparent, "RGB"]]

This is due to the fact, that Transparent is GrayLevel[0,0] and is incompatible with the ImageColorSpace of your image p (Automatic, which means that no color space is specified).
You can also convert your image into a specific color space, e.g.

ImagePad[ColorConvert[p, "Grayscale"], 10, Transparent]
ImagePad[ColorConvert[p, "RGB"], 10, Transparent]
  • $\begingroup$ Thanks for the asnwer, it's very helpful. I didn't know that the problem was from color space. TheAutomatic comes from importing a video. $\endgroup$ – xslittlegrass Sep 6 '14 at 18:00
  • $\begingroup$ It' s strange that a figure in the documentation also has the color space goes to Automatic, but padding transparent works.See my update. Do you know why? $\endgroup$ – xslittlegrass Sep 8 '14 at 23:32
  • $\begingroup$ @xslittlegrass Its Automatic is different, as it has only one channel (use ImageChannels@p to check) compared to the 3 channels of your original p. $\endgroup$ – Karsten 7. Sep 9 '14 at 16:24

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