Transparency option is not working both for makecpt and grdimage

Q&A
, ,
1

Hi, I am trying to apply transparency for makecpt and grdimage, but there is no effect. Following is my code. As I know, modern GMT can apply transparency only on pdf, but in my case, I applied for several image formats, including pdf, ps, jpg, and png, but I didn’t get much success. In addition, I am using an external cpt file here, but I also tried with the default cpt files of GMT. Is there any issue with MacOS? I am using GMT 6.4.0 on Macbook Pro. I used a similar option in the previous version with Linux, which worked perfectly.

gmt begin mean_no2_new pdf A+m0.1c,E900 -C

j=-JM8
r=-R-105/-101/30.8/33.2
cpt=f-33-13-10.cpt

gmt makecpt -T-0.2/4.5/0.01 -C$cpt -A50+a -H -D -M > map.cpt
gmt grdimage grdfile.nc $j $x $y -BWSne -Cmap.cpt -t50
gmt coast -Df -Wthin -Na/0.5
gmt colorbar -DjBL+o9.2c/0.5c+w4.5c/0.35+ma -Cmap.cpt

gmt end
2

Perhaps your ghostscript (gs) has been updated to 10 and then you need to run GMT from the latest source since 6.5 is not yet out. I think that is what is happening. Many of us use macOS and no problem but 6.4 does not expect gs 10.

3

Alternatively, step back to gs 9.54 or whatever the last one was.

4

Thanks, @pwessel. I step back to gs 9.56.1, and it works now. However, I have seen that when I applied transparency to makecpt. It can be visualized in the colorbar, but the same cpt with transparency applied to the grdimage is not visualized in the end product. Although I can use -t50 on grdimage, I am curious to know why a cpt generated with transparency is not working on the grdimage. I attached an end plot here. I am using the above code without -t50 in the grdimage line.

test_plot
test_plot3949×2247 311 KB