Fetch and display uncompressed pixel values in web browser

Question

Suppose I have get json data like this from an HTTP server:

{
     "width":1234,
     "height":356,
     "channels":"rgba",
     "sample_type":"uint8",
     "intensity_transfer_function":"sRGB",
     "pixels":"<encoded raw pixels>"
}

Here, it is assumed that pixels are not encoded using JPEG or PNG. Instead the data contains "displayable" pixels, where the string

• Consists of either pairs of hexadecimal digits (ff0000ff would mean a red pixel), or

• Is a base-64 representation of all pixel values

Is it possible to show the data in a web browser using JavaScript, or do the server have to send it as a PNG?

As a side note: The above sets sample_type to uint8 and intensity_transfer_function. This can be represented by a PNG, so there would be no information loss there. However, I am also interesting in dealing with stuff that are outside the PNG spec, such as sample_type float32 and intensity_transfer_function set to linear, to not loose any information sent by the server.