ST_PathFillMode color shade calculation method...

Question

Hi,

I am using ECMA-376 spec which defines PathFillMode is defined as follows

darken (Darken Path Fill) This specifies that the corresponding path should have a darker shaded color applied to it’s fill.
darkenLess (Darken Path Fill Less) This specifies that the corresponding path should havea slightly darker shaded color applied to it’s fill.
lighten (Lighten Path Fill) This specifies that the corresponding path should have a lightly shaded color applied to it’s fill.
lightenLess (Lighten Path Fill Less) This specifies that the corresponding path should have a slightly lighter shaded color applied to it’s fill.
none (No Path Fill) This specifies that the corresponding path should have no fill.
norm (Normal Path Fill) This specifies that the corresponding path should have a normally shaded color applied to it’s fill.

This is too vague to understand.

Does anyone know the exact way to calculate the values of these shades given a color and fillMode.

Thanks in advance

--

 

 

Answer 1

Hi Commando_dhruv:

I have alerted protocol documentation team regarding your inquiry. A member of the team will be in touch soon through this thread.

---

Regards, Obaid Farooqi

Answer 2

commando-dhruv,

I am the engineer who has taken ownership of your question. I am currently investigating this matter and will update you as things progress.

Dominic Salemno
Escalation Engineer
Open Specifications

Answer 3

commando-dhruv,

I am still investigating this issue and will update you on this matter shortly.

Dominic Salemno
Escalation Engineer
Open Specifications

Answer 4

commando-dhruv,

darken/darkenLess and lighten/lightLess are calculated based off a simple blend of black or white respectively:

darken – 40% blend of black

darkenLess – 20% blend of black

lighten – 40% blend of white

lightenLess – 20% blend of white

I hope this assists you.

Dominic Salemno

Escalation Engineer

Open Specifications

Answer 5

Would these blends affect the alpha component or is that left alone?

Also, does PowerPoint do some kind of special rounding on resulting values. I noticed that the blend PowerPoint does is not 100% accurate with the numbers you listed above. For example:

	R	G	B
Normal	79	129	189
lighten
PowerPoint	149	179	215
Calculation	149.4	179.4	215.4
lightenLess
PowerPoint	114	154	202
Calculation	114.2	154.2	202.2
darken
PowerPoint	47	77	113
Calculation	47.4	77.4	113.4
darkenLess
PowerPoint	64	104	152
Calculation	63.2	103.2	151.2

This was tested again the 'bevel' shape. You'll notice in darkenLess, the Red, Green and Blue values (highlighted in red) are rounded up in PowerPoint, inconsistent with the rest of the calculations. I've tried in this in sRGB 0.0-1.0 space as well and the inconsistent rounding results are the same.

 

Answer 6

Terlo,

I am still investigating this.

Answer 7

Terlo,

The alpha component is not affected by the blend.

When the transforms are cast back to a byte after calculation, this is how the values are affected. There is nothing special done in terms of rounding. This is how the values worked out.

 

Answer 8

Great, thanks King for the details. Appreciate it!