Passing Transparencies

there is an assumption that is made when mapping a transparency into another component. i was going to post this as a bug, but it's probably not really a bug and may just be i need an explanation.

if you look at the posted picture, my assumption would be that the component on the right shld be showing the transparency of the component on the left. but, it doesnt. now, i know the alpha channel is a separate channel from the HLS, so from that standpoint the transparent part wouldnt show in the HLS.

but, that leaves the question of where did the alpha channel go? and in the 2nd image i'm posting here, i added a get alpha but it's all white. and that just leaves me confused.

do some components not pass the alpha channel along? arent all the components operating in 32 bit, 4 channel? the blend component seems to work fine, but some of the others seem odd in this respect.

but like i say, it could just be that i dont understand what's going on here.

It's obviously not a bug.

Look at the image below. Although the new alpha gets multiplied into the source image for the thumbnail display purposes, the 3 Extract RGB components can still extract the unmultiplied RGB channels. So there you go, we have a clean 32bit RGBA.

Conclusion: Since the Extract XXX components only ever extract one channel, regardless of any alpha present, naturally, they don't pass along the transparency.

At an Extract component, 3 of the 4 channels are basically discarded, or rather, the three image channels are overwritten with the contents of the selected channel, and the alpha is discarded.

Very enlightening and well explained, thanks for the knowledge ........ Carl

thanks, vlad. yes, i've noticed this about the transparency passing. drives me nuts at times trying to figure what gets passed and what doesnt, but i'm getting there.