increasing dpi on a jpg when sending

Mark Krutke · Post by **Mark Krutke** » 24 Apr 2002 7:22 pm

Does anyone know if there exists a program where, say I have a jpeg, and I want to send it, but increase the dpi, so the person who recieves it gets it as jpeg with 300 dpi instead of 150 dpi. I've tried other files (GIF, TIFF, BITMAP, etc.), and I still get 300 or less, it seems. Is there an option or some program that can do this?

Ron Castle · Post by **Ron Castle** » 25 Apr 2002 2:06 am

Adobe Photoshop

Bill Crook · Post by **Bill Crook** » 25 Apr 2002 4:57 am

Mark....

If the resultant jpeg is to be viewed on a computer only, It dosen't make any matter what the DPI is. The best a computer monitor can do is 72 DPI. The rest goes into the bit-bucket. At 300 DPI, this is good enought for printinng in most cases, but it's not exactly 35mm quality.

As for using "PhotoShop", I have the program and it makes for VERY large files. A 800 X 600 photo can be as much as 4-9 meg in size. Most IPS will not allow one to up-load such a large file. (While it can be done,there is a trick to it.)

And if you increase the DPI from 150 to 300, you make the picture twice as large, often times too large for the complete photo to be viewed.(on a computer monitor) There are trade-offs here. While this can be adjusted for, it tends to be very "PhotoShop" intensive.

Personally, I would suggest staying with the native mode for computer use.

Jeff Agnew · Post by **Jeff Agnew** » 25 Apr 2002 8:33 am

so the person who recieves it gets it as jpeg with 300 dpi instead of 150 dpi.

Yes. Almost any competent graphics program allows you to adjust the size parameters of an image. Photoshop or PaintShop Pro, for example. The real answer is, "It depends." If you tell us your intended purpose we can give you better advice. Do you want to do this to increase quality for printing?

If so, what size do you want the print?

Photoshop can definitely "rez up" a print but whether or not it will be good enough quality depends on your intended size, type of printer, and viewing distance.

Genuine Fractals does a better job on large prints and for those printed by labs.

Be aware that, as Bill mentioned, the size of your image in pixels has absolutely no relationship to its final printed size.

As for using "PhotoShop", I have the program and it makes for VERY large files. A 800 X 600 photo can be as much as 4-9 meg in size.

But this not because of anything inherent to do with Photoshop. You can make an 800x600 image of almost any file size, depending on the file format and bit depth. Native Photoshop formats are large because they contain layer info, alpha channels, masking info, etc. You'd never send a .psd file to someone else except for editing.

Mark Krutke · Post by **Mark Krutke** » 25 Apr 2002 2:29 pm

Thanks.

My application is that I need to send a picture to a CD Duplicating manufacturer for 'on CD printing' and I wanted to send it from my computer so that the manufacturer would have to redo it (to avoid set up costs), thus wanting the higher dpi so the image could appear clearer, more distinct, etc.

Bobby Lee · Post by **Bobby Lee** » 25 Apr 2002 3:20 pm

Okay, since I write graphics software for a living, let me try to explain it.

DPI stands for dots per inch. A dot is a pixel.

Suppose you have an image that is 600x600 pixels. If you print it at 1" by 1", you could call it a 600 dpi image. Or you could print the same file at 6" by 6" and say that it's a 100 dpi image. You don't have to change anything in the image file to do this!

Almost all printing software allows you to resize the image. The smaller you print an image, the greater the DPI. DPI is not a attribute of the image file - it's a function of the printing process.

Some graphics formats include a DPI recommendation. It is used in page layout software to set the initial size of the picture on the page. You can then resize tthe image before you print it, overriding the "recommendation".

If you want to increase the pixel size of an image, the computer has to use an algorithm to "invent" more image detail. Most graphics programs will do this, but the result often isn't any better than letting the page layout program increase the size.

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<img align=right src="http://b0b.com/b0b.gif" width="64" height="64">Bobby Lee - email: quasar@b0b.com - gigs - CDs
Sierra Session 12 (E9), Williams 400X (Emaj9, D6), Sierra Olympic 12 (F Diatonic) Sierra Laptop 8 (D13), Fender Stringmaster (E13, A6)[This message was edited by Bobby Lee on 25 April 2002 at 04:25 PM.]