Masks - Creating and work

[Peter R]

Hi everyone
Lately I've been using Corona render more and more. Everything is fine but I have a question about post-processing images in photoshop.
I worked at V-Ray for a long time. Often use Render_ID channel.
Scheme of work:
- for greater compatibility I use 16 bit;
- channel Render_ID to v-ray;
- I use to highlight the desired color - Magic wand
- putting the point Tolerance-0, uncheck all other points I achieved excellent accuracy of selection.

The question is - in Corona I can't achieve the same accuracy of the selection by magic wand in photoshop. The selection is poor, insufficient. Setting the checkbox to different positions and changing parameters does not help.
Someone faced such problem?

PS the Creation of a special masks are not considered as a solution. interested in working exclusively with ID channel.

Thanks

[maru]

We've received some reports that masks in Corona are sometimes not "pixel-perfect". We will definitely look into this. If you can provide some examples (even some simple scenes), please do.

[Peter R]

I made test renders to make the question and problem more clear.

Software used:
Max 2015
V-Ray 3.6
Corona 2.0
PS

Shown pictures-a fragment of a picture with a resolution of 3500 on the wide side
Render time-15-30 minutes;
the magic wand setting is also shown. The language is not English, but everything is clear.

For V-Ray rendering time was not enough, the mask is not smooth, but still the accuracy and convenience of selection is better.
Corona in my opinion did not cope with the task.
At the same time, I showed the extreme option - when the selected objects are placed on a neutral background. During operation, during post - processing this is not required-mask and ID channel is used for color and light correction.

Options for problem 2:
1. ID mask problem in Corona;
2. Need tips on using Corona and PS

[maru]

What is clear in your pictures is that the mask from V-Ray does not have any antialiasing.
You can get the same thing in Corona using a string option.

Here is how to do it:
1. Render your beauty pass normally
2. Once the beauty pass is rendered, go to Render Setup > Scene and enable "Render only masks (disable shading)" option - this will prevent rendering the beauty pass again, so you will be rendering masks only
3. Use this string option to completely disable antialiasing: https://coronarenderer.freshdesk.com/support/solutions/articles/5000516183
4. Render your mask

I am attaching example renders from V-Ray and Corona and the scenes.