When using the vibrance MSL filter from the file vibrance.msl, applying a parameter value of -0.01 results in a significantly more saturated image compared to using 0.01. This asymmetry is unexpected; ideally, small positive and negative adjustments around zero should produce similar visual effects in the opposite directions. Notably, only when the negative parameter reaches around -0.3 does the output start to approximate the effect of a 0.01 value.
Steps to Reproduce:
Clone the repository or open the vibrance.msl file.
Apply the vibrance filter with a parameter value of 0.01 and observe the image’s saturation.
Apply the vibrance filter with a parameter value of -0.01 and compare the saturation level.
Optionally, increase the negative parameter gradually (e.g., -0.05, -0.1, -0.3) to see how the effect changes.
Expected Behavior:
Minor adjustments to vibrance (both positive and negative values near zero) should result in similarly scaled changes in image saturation, with the signs only affecting the direction of the change. A value of -0.01 should not cause a significantly higher saturation compared to 0.01.
Actual Behavior:
A vibrance value of -0.01 produces much higher saturation than a value of 0.01. It takes a negative value of approximately -0.3 for the saturation effect to match that produced by 0.01.
Impact:
This inconsistency might lead to confusion for users attempting to fine-tune image saturation. It also indicates a potential bug in the calculation or implementation of the vibrance effect within the shader code.
Additional Notes:
Verify if the asymmetry in behavior is intentional (e.g., for artistic purposes) or a coding mistake.
Consider reviewing the math handling positive and negative vibrance values to ensure symmetric behavior around zero.
When using the vibrance MSL filter from the file vibrance.msl, applying a parameter value of -0.01 results in a significantly more saturated image compared to using 0.01. This asymmetry is unexpected; ideally, small positive and negative adjustments around zero should produce similar visual effects in the opposite directions. Notably, only when the negative parameter reaches around -0.3 does the output start to approximate the effect of a 0.01 value.
Steps to Reproduce:
Clone the repository or open the vibrance.msl file.
Apply the vibrance filter with a parameter value of 0.01 and observe the image’s saturation.
Apply the vibrance filter with a parameter value of -0.01 and compare the saturation level.
Optionally, increase the negative parameter gradually (e.g., -0.05, -0.1, -0.3) to see how the effect changes.
Expected Behavior:
Minor adjustments to vibrance (both positive and negative values near zero) should result in similarly scaled changes in image saturation, with the signs only affecting the direction of the change. A value of -0.01 should not cause a significantly higher saturation compared to 0.01.
Actual Behavior:
A vibrance value of -0.01 produces much higher saturation than a value of 0.01. It takes a negative value of approximately -0.3 for the saturation effect to match that produced by 0.01.
Impact:
This inconsistency might lead to confusion for users attempting to fine-tune image saturation. It also indicates a potential bug in the calculation or implementation of the vibrance effect within the shader code.
Additional Notes:
Verify if the asymmetry in behavior is intentional (e.g., for artistic purposes) or a coding mistake.
Consider reviewing the math handling positive and negative vibrance values to ensure symmetric behavior around zero.