Is there an "official" standard usage of Red and Green on differential gene expression heatmaps? I have recently found myself making multiple heatmaps for visualization of differential gene expression results between replicates in two experimental conditions.
The default settings in the plotting software I use color:

Upregulated genes --&gt; red
Downregulated genes --&gt; green
Unchanged genes --&gt; black

My intuition screams at me that this color scheme is reversed, and that upregulated genes should be green and that downregulated genes should be red. I have asked several labmates about their intuition regarding this color scheme, and have found about a 50/50 split in those that intuitively agree with each different scheme.
In my searching on this topic, I have found that several programs plot heatmaps with the same default colors as the program I'm using (red=upregulated, green=downregulated). Additionally, I have been told in conversation that this is essentially an accepted standard.
If this is indeed the convention, I will begin trying to rewire my intuition, but I want to confirm that it is before I do so. However I have not yet been able to find any &quot;official&quot; guidelines from agencies, publishers, authorities in the field, etc., specifying the use of red/green in heatmaps.
I do know that there are many suggestions for alternative heatmap color schemes, but I'm interested in finding an official answer for the red/green scheme specifically.
Edit: Several comments have stated that there is no such standard as described above. Therefore I am modifying the following question somewhat to:
Are there &quot;official&quot; guidelines from agencies, publishers, authorities in the field, etc., specifying the use of red/green in heatmaps?
Or conversely are there any “official” guidelines stating that there is no such specification and/or that any such selection of colors is acceptable?
As others already pointed out, there is no official heatmap color scheme. I am not sure there is an official color scheme for any other types of plots either.
However, heatmaps seem to be far more standardized. Traditionally, heatmaps have been red-black-green as you originally stated. Most heatmaps from the microarray era and early RNA-seq are like that. You can have a heatmap for any type of data, but the majority is for gene expression. A lot of tools and tutorials were written back then, so they have that color scheme. From about 2008 to 2012, most people switched to the red-white-blue (or red-yellow-blue) color scheme. Switching green to blue avoids the color-blindness issue. Switching black to white is better for the ink if you print your papers and generally looks better on white background.
I originally found red as high to be confusing because I was thinking in financial terms (if the market is red, it's down). Now I think of it as a water faucet (red is hot, blue is cold).
Edit: In the last year or so, the viridis palette started to become widely used. It's far from the standard, but could become more popular in the future.