Photoshop sep file size

[Dottonedan]

Good morning boarders!


Every now and then, I get a file from someone (or even a new file I created) and see that the end result separation file is actually very large. Much larger than normal. Like just a couple days ago, I had a file that was 400mb .psd greyscale sep channels. Typical size, tryical quantity of colors. Like I think it was 7 clrs at 13x16" in doc size, at 300 rez.  400mb?


A typical sep file ranges from 10mb-40-45mb max on average. Maybe 3% of them are like this. But why?  So I try other methods. Maybe it's something in my settings/preferences. I donno. Can't find anything on it.


Any other Photoshop users that have ran into this and found any answers?  I will dig further on Adobe forums, or something but thought I'd give this aa shot also.

[Nation03]

That seems really high. Not sure why either. Other than the stuff i send you, I do all my seps in layers, not channels. I don't know if that impacts the file size. I did a 5 color job yesterday that is about 13mb. Print size was about 11x8 inches with resolution at 600. I'm curious why a file would be 400mb.

[3Deep]

When a file size gets very large I'll try going down on my rez from 300 to half like 150 and guess what I don't lose much detail if any at 150, even 200 rez size file if the art is at the size you need to print, works pretty good at-least in my eye it looks good.

[Chadwick]

I haven't seen ( noticed? ) that very often, then again I'm not always looking at file sizes if it's local stuff.

I did have one instance where I converted my original CMYK .psd file down to RGB, saved that as well, and wound up with a larger file.
How a 32 bit color depth file can be smaller than a 24 bit color depth had me scratching my head.
Never did investigate further..

[Dottonedan]

As it turns out, I'm pretty sure now that the difference was wether my file sent to me was an 8bit, 16bit, 32bit.


This is a bit (no pun) different than what Chadwick was mentioning. Bit depth describes how much color depth an individual pixel can have.


1bit  Can be a black or white,
8bit  256 shades of grayscale - 0-255 shades of grey (per channel)
8bit RGB Color 256x 3 channels = works out to 16 million colors and can be referred to as a 24bit file (As Chadwick had mentioned). A CMYK file at 8bit color depth can be called a 32bit color file (8x4).


Most of us work in 8 bit color mode.
There are options to work in 8, 16, 32, color bit depth.   (IMAGE, MODE, BIT DEPTH).

In my case, someone sent me a file that was 16 or 32bit color depth that resulted in a file that was near 10x my file size I normally work in.

There is also a HRD (High Dynamic Range) mode of bit depth. This I is only under RAW format. HDR is used more while working in Photography and getting the most options out of your luminance (darks and lights).

[Sbrem]

Interesting, as I run into this on rare occasion too. However, I've read many times that the file resolution only has to be twice the line count, so that mega file can be reduced to say 130 ppi for a 65 line halftone before placing it into Illustrator (maybe Corel too, I don't use it) ... Not that it answers the question, but is a good workaround.

Steve

[Dottonedan]

Today, with most screen printers using digital output of some sort, I feel this 2.5 times rule is no longer adequately used and your file should be at least 300 if not 600. Apples to apples. The files looks worse if I were to output seps at 100 Rez for 50lpi.   Many of us also design using type in Photoshop. It used to be said the you can't do small type at all in raster or photoshop, but with higher and higher resolutions being used, it's not a problem to do 12pt time Roman in Photoshop at 600ppi (screen printed).  This was not intended by Adobe. They want you to use their other reprograms for type building and is part of why they give the suggestion to do 2x the lpi.


The one major factor (for me as a separator) for preferring higher resolution files is the fact that higher Rez files separate out...and print cleaner, tighter, more precise than say a 300ppi file.  I don't want to "pull color separations"from a 100 rez file because I am printing at 50lpi.  The (2x the lip) may apply more so without degradation if one were printing straight CMYK or a greyscale (without having to manually break the colors up or even use an auto separation program and would just print straight from the file as is.

[Sbrem]

I like to do the rasters in PS, then import to Illustrator and do the text there, which is why I can use the lower res, but I work in 300 to 600 ppi, and save a duplicate to the lower res for output. I'll need to dig in a little more when I get a chance. I did years ago make a test, and couldn't detect a difference. Text in PS is definitely 600. And, a long time ago there was discussion on raising the output resolution as high as you can go when making a bitmap halftone, the dots just come out much better, and then it's a bitmap, which has a low file size. I gotta get a life...

Steve