Do Calculations and Apply Image use the Standardized Math, or 0 - 255

[Laurence-Baker]

I know Blend modes in Layers use the Standardized system, 0 equals black and, 1 equals white.

Is the Standardized system used in Calculations and Apply Image Blend Modes? Or, the normal 0 - 255 system?

[Test Screen Name]

All blend mode maths is defined in terms of 0 to 1, but the actual calculations are very likely done with integer ranges for efficiency. We can't know and usually don't need to know. What is behind your question?

[Laurence-Baker]

Thanks, just curious really. The reason I ask is because the Offset using 0 - 255 system. I realise under the hood it might be using a different system.

[Test Screen Name]

You can expect things to be converted to what the image uses internally at least. It might use 0-255, 0-32768 or a 32-bit value according to the image mode. The 0-255 system became so well established because that is the actual pixel value in an 8 bit field, which is what is found in many image formats and hardware for talking to monitors. I find the CMYK convention just weird: nobody complains that the 255 values in an 8-bit CMYK image are reduced to 101 specific values.

[Laurence-Baker]

Thanks

My innumeracy lets me down at lot.

Eyeballing Multiply in Calculations, used on the same channel in S1 and S2, seems to do what Multiply does elsewhere - darken it.

I'm guessing Adobe will continue to support Apply Image, and Calculations. I consider them to be legacy commands, as Selecting is becoming better with every version.

I see a lot of videos on YouTube showing pointless tricks with Calculations which could be easily done in a few steps with the normal tools and blend modes.

I'd like to know what experienced users of Photoshop think about how useful Apply Image, and Calculations are.

Thanks

Laurence

[davescm]

I'm guessing Adobe will continue to support Apply Image, and Calculations. I consider them to be legacy commands, as Selecting is becoming better with every version.

Hi

Calculations is very useful when making channel based selections and for some images that is the best way. I welcome and use all the newer selection tools but occasionally the best way for an image (or a difficult part of an image) is to take a channel, or channels, and use that with calculations (and it may be the channels have to come from a different mode such as Lab).

Dave