Ariel:

You never need to do a job with 800 dpi at real size. 

800dpi is for scaled down document, not actual dimension.

If work on actual dimension, 300dpi is optimum as you suggested.

we are using software with origins in desktop publishing.  because that industry has a fixed viewing distance, it makes sense that they look at dpi as some golden rule to be followed.  it took me lots of lost time and money to discover this rule...

dpi decreases as size increases.  there is no optimal dpi to work in because with signs, viewing distance varies.  try reading a 50' sign from magazine reading distance (18" away.)  you cant read it at all.  no need for magazine resolutions when youre not reading a magazine.  sure, the flies landing on your vehicle wrap will be impressed with your 300 dpi's, but no one will ever be able to see the entire vehicle that close up.  how did people do large format back when the badest computer was 800 mhz sporting tens of gigs rather than the hundreds now standard?  they used dpi calculation.  well, vector design is a better answer, but that's a different rant. 

the math:

resolution² * width * height * bits per sample = filesize in bits

8388608 bits = 1 meg;    60 meg * 8388608 bits/meg = 503316480 bits

so, to reverse it into a useable formula so you know what dpi to work in, algebra says:

sqrt((((503316480 / 24) / w ) / h)) = your dpi, where w & h are in inches and you are working in rgb (24 bits/sample)

of course, this will give you a dpi that is too high for really small things, but again, that's a different industry.

example:

got a series of windows measuring 72" x 240"  they want to put lifesize prints all along it.

sqrt((((503316480 / 24) / 72 ) / 240))  = ~35dpi

i used google to calculate it.  the link

so wow! 35 dpi for something that needs to look good?!?!?  people are going to be walking past that!  wtf?  that's way too low.

well, at 20' long, it can only really be fully seen from much farther away, so 35 dpi will truly surprise you how good it looks.  try it out. 

sure, there are rare exceptions like maybe you need to print a readable bible that spans 20'.  35dpi wont cut it...but neither would 300 dpi because you still have to save the file and go to sleep at some point so that's where vector art comes in.

if you want to know, 6'x20'@ 300dpi (((300^2 * 24) * 72 ) * 240) / 8388608 = ~4500 meg  maybe not that huge for modern day equipment afterall, "hard drives are cheap" "ram is cheap" "blah blah blah."  well time has gone up in price, and networks/hard drives havent become proportionately faster.  you can make it happen if you spend the time, but why?  just to follow the standards of the desktop publishing industry with it's fixed viewing distance? 

but anyway, to answer the original question, drop shadows pretty much suck.

introducing a one into vector workflow means switching to bitmap exports because no cheap printhouses can open your .cdr file.  well at least now you know how to export bitmaps.

Chet, thanks for the formula, it will defintely be very useful.

Btw, there is one part that I don't understand:

chet:

resolution² * width * height * bits per sample = filesize in bits

8388608 bits = 1 meg;    60 meg * 8388608 bits/meg = 503316480 bits

How do you get the number 8388608?

chet:

but anyway, to answer the original question, drop shadows pretty much suck.

introducing a one into vector workflow means switching to bitmap exports because no cheap printhouses can open your .cdr file.  well at least now you know how to export bitmaps.

Although Anand suggested in the other thread that PAINT will do as fine as PhotoShop, I still prefer PS when dealing with pictures or effects.

A tool like the attached allows you to render shadows at whatever you like. Plus, no more glitchy shadows, and they look smoother at the corners. The text in the shot below is about 64" wide! And only took seconds to render as a separate CMYK bitmap.

more info here

llvlludassar:

Thank you very much Ahmad Ajlouny, i reduced rendering resolution to 72dpi and file size is much lighter now but still it's way heavier as compare to regular file, do u think 72dpi will do for big formats like 10' by 20'.

Hi Michael

I have been following this thread since it started. Many experts have added contents and have added to my knowledge even. I don't work much with signboards. I have not used PS since its version 3 & now its CS3. I did not had to shift to any other application. May be I did'nt had a kind of job that forced me to shift. And obviously there was no struggle for getting the desired results as you are. It is convenient for me to work on single platform i.e. CorelDRAW Suite.

MichaelTadashi:

Although Anand suggested in the other thread that PAINT will do as fine as PhotoShop, I still prefer PS when dealing with pictures or effects.

MichaelTadashi:

Although Anand suggested in the other thread that PAINT will do as fine as PhotoShop, I still prefer PS when dealing with pictures or effects.

You can use Photoshop instead PhotoPaint, but there's not any advantages for this; it's best that you use the program that you know more.

Ariel:

You can use Photoshop instead PhotoPaint, but there's not any advantages for this;

So you mean using Draw-Paint has certain advantage over Draw-Shop?

Ariel:

it's best that you use the program that you know more.

I've never learned to use Paint. PhotoShop is the only one I used in the past, and started learning Draw 2 months ago.

CorelDRAW/Photoshop works fine, but PhotoPaint is part of the CorelDRAW suite. You can edit a bitmap indide CorelDRAW easily. Of course, you can do this also with Photoshop, if you choose "external link" whem import, and edit the original file using the Link Manager. But Draw/PPaint are part of the same suite, and have more compatibity, so is more easy to work with both. You can open in PhotoPaint a vector file, saved as CMX with CorelDRAW. If you convert to bitmap in CorelDRAW, the internal file format is CPT, the same as PhotoPaint.
Corel has others photo-editing programs, such as PaintShopPro, Painter and the "new" and great PhotoImpact. But the best for work with CorelDRAW is PhotoPaint.

I use Photoshop and other software too. You can do some jobs more easy if you work with both programs, For example, if you want a bitmap with transparent background: Select the object or the desired area in Photoshop (normal selection: rectangle, circle, magic wand, lasso...) and Save selection in the Select menu. That's all. It's the same of "save selection as channel", in the Channels flyout:  the results is a new hannel, called Alpha Channel. Save as TIF and import to CorelDRAW, You don't need to erase the background, make a new layer, create a pah or anything. Only select, and save selection.
Of course, you can do the same in PhotoPaint, with a little difference: if you change something inside CorelDRAW, PhotoPaint remains and stores these changes. If you edit the original file with Photoshop, the changes made in CorelDRAW will no saved, and you need to Export as a new file, then open, edit, save and import again. With PhotoPaint, you only need to edit (inside CorelDRAW), and close PhotoPaint when finished,

Chet, where have you been? I've been waiting for you since the beginning of the thread. Thank you for your generosity in giving us what costs you "lots of time and money".

chet:

resolution² * width * height * bits per sample = filesize in bits

8388608 bits = 1 meg;    60 meg * 8388608 bits/meg = 503316480 bits

so, to reverse it into a useable formula so you know what dpi to work in, algebra says:

sqrt((((503316480 / 24) / w ) / h)) = your dpi, where w & h are in inches and you are working in rgb (24 bits/sample)

in the equation

1. File size is fixed: "60 meg"!
2. Color Depth affects the resulting value of DPI.
3. Since the equation does not contain a Distance variable, I think it assumes that Distance will increase when Width and Height increase.

I think I should figure out the appropriate DPI given

1. Width
2. Height
3. (Distance)

Without the Color Depth variable and "60 meg" File Size constant. And the physical sign (sign material + ink dots) should be at this DPI, whether it is printed from a vector or a bitmap application.

In other words Chet,

chet:

resolution² * width * height * bits per sample = filesize in bits

This is a general equation to calculate file size for a bitmap without compression.

chet:

sqrt((((503316480 / 24) / w ) / h)) = your dpi

And this is the same equation rearranged to calculate DPI for a certain bitmap (60MB RGB) without compression.

Thanks Lads for your kind infomration and guideness it really helped me to gain my knowledge, i am happy to join corel forum . Sorry michael Tadashi blank document size was 126 mb , i did make mistake .

So you started at 126MB but the final output was heavily pixelate?

Hi MichaelTadashi,

                             I did try again your method and result is as followed:-

1) Blank Document deminsion 8"x4" ,800 resolution, Cymk ( Blank document size 78.1mb)

2) I designed sign and used 2 extra large good quality images, moreover i included shadow effect for text

3) Exported it as a jpg on high quality ( finished size 2.08 mb)

4) For printing purpose i expanded size to 8'x4' in versawork software ( result was good no pixel brken )

Thanks

llvlludassar, glad to hear that.

Cheers.

Chet,

I reread my replies to your post, and thought they might be misunderstood.

chet:

Thank you for your generosity in giving us what costs you "lots of time and money".

chet:

Chet, where have you been? I've been waiting for you since the beginning of the thread.

I hope you would accept my apologies, and wish to hear your comments on my previous posts.

Ahmad Ajlouny