Resizing a 1x1 to 2x2 size or vice versa?

[Gasman]

Hi all

Probably a piece of cake to you experienced imagers but I`ll ask anyway

I`m new to ccd imaging having just got an Atik 314L plus filter wheel recently. I took some fits of M42 the other night and after reading some tuts on RGB I took a few Luminance fits with no binning (or should that be 1x1 the same thing?) a few Red,Green and Blue fits all at 2x2 binning so after using Deep sky stacker I now have 4 master L,R,G and B fits files. Now using PS CS2 I`m going round in circles trying to resize the 1x1 L file to the same size as the other 2x2 binned files but no joy. The Luminance image I get on screen says its at 50% and is the same physical size as the other files which say they are 100% but making the L file 100% simply doubles its size on screen so I can`t paste it on to the merged RGB image to get an LRGB image how do I resize it so I can paste it onto the RGB image please?. (Or should I double the RGB image size??)

Thanks

Steve

[gkec]

There are probably people on here that know more about PS than I do but I know about binning. The binned images will be half the dimensions of the unbinned image in each dimension. So to use them you probably have to "bin" the unbinned images so that they are the same size as the binned images. There is an issue with readout noise here in that the binned unbinned images will have 4 time the readout noise of the binned images if you see what I mean. When I say bin I mean that each box of four pixels is average to get the pixel value. Reducing the zoom is not the same thing.

What I don't quite understand is what you mean by physical size. You should always work in pixels, any information that infers the actual real world image size is best ignored. If you mean file size on the disk then I'm not sure.

So I think what you need to do is reduce the unbinned images by half in each direction. TBH I don't think photoshop is probably the best tool for doing this. Also someone who knows more about PS than me might come along soon.

[Freddie]

It sounds like you are using the zoom tool to change the %. You need to go into the image tab and then change the actual image size.

[RikM]

Keep the L image at full size and resize the RGB to match it. All the detail will be in the L, the RGB just adds the colour. As said above, you need to use 'Image -> Image size' then change the resolution, width and height values to match your luminance image.

I future, you would probably be better to use the 2x drizzle feature in DSS for your R, G, & B stacks. They will then be the same size as the 1x1 Luminance before you combine them.

[Gasman]

Thanks Peeps thats cracked it ;-). I was trying to just change the image size of each RGB instead of the resolution . Just come across Annies actions which seems the dogs whatsits. I just need to suss out how to align the frames in PS!

Thanks again

Steve

[Freddie]

Your best bet is to ensure all your frames are aligned the same in DSS. You can do this by manually setting the same reference frame for each stack. If you use a frame from the L captures, just make sure you don't have it selected to actually be included in the R, G and B stacks, just use it to set as the reference frame.

[Gasman]

How would I do that Freddie?. If I`m stacking a set of maybe 20 Red fits would I include a frame from say the Luminence set to use as reference and then include the same frame with the Blue and Green sets when I stack them?.If so does that not have an effect on the resolution of each coloured stack if an uncoloured frame is included, if that makes sense. I thought with LRGB processing the object is to get a stacked image of Red, one of Blue, then a Green one and finally a Luminance so we are left with 4 images to be aligned and merged. I`m just wondering what a non-red frame would do to a stack of red frames ( rereading that sounds cobblers but I hope you get the drift )

Best

Steve

[Freddie]

Steve, that's correct, you don't actually want the L included in the R,G and B stacks hence me saying make sure you don't select it to be stacked i.e. make sure there is no tick next to it in the file list. Even when it isn't ticked, you can still manually select it as the reference frame. Hope that makes sense.

[ollypenrice]

Although it's not cheap the programme Registar is the absolute king of image alignment. I use it all the time. It can also resize and align images of totally different image scales from different scopes.

Olly

PS, Gasman, I see you some Leica 8x42s. Good, aen't they?!

[dph1nm]

1x1 to 2x2 size or vice versa

Note that this process in not reversible. You can bin from 1x1 to 2x2 and not lose signal-to-noise, but you cannot resample back from 2x2 to 1x1 without losing information.

NigelM

[Gasman]

PS, Gasman, I see you some Leica 8x42s. Good, aen't they?!

Thanks for the excellent info chaps, massive help!. Yes brilliant piece of kit they are Olly. I also have the Leica 77mm Apo birding scope too, wish they did bigger astro scopes, first time I`ve seen star colours using that

Steve