Confused

Do you have photoshop?

Open your files in PS and look at the image dimensions. Do not upsize it….but, change to 300dpi and then adjust the dimension so they are the same file size.

In fact, most print house provide you the template you can open in photoshop, drop your artwork in, delete their template and then send them back the file. PSD

"Wolf" wrote in message

hi
Need to print some cd covers.
The print company guy has confused me- says he needs images at 300dpi. I tell him that mine are 72 dpi (3264 x 2448 pixels from camera image) and he says that’ll be Ok.

Could’t I just upscale the image in PS to 300dpi?

I don’t beleive that my camera, Panasonic fz30, will do 300 dpi (I’ll read the instruction book if i can find it!! )
Can some one post a website or advise how I can understand the difference.

Wolf wrote:

hi
Need to print some cd covers.
The print company guy has confused me- says he needs images at 300dpi. I tell him that mine are 72 dpi (3264 x 2448 pixels from camera image) and he says that’ll be Ok.

Could’t I just upscale the image in PS to 300dpi?

I don’t beleive that my camera, Panasonic fz30, will do 300 dpi (I’ll read the instruction book if i can find it!! )
Can some one post a website or advise how I can understand the difference.

There’s a lot of confusion about dpi. Fact is dpi – dots per inch – is a printer function, and can be changed in PS without affecting the image at all. Currently, your 3264 x 2448 image at 72dpi would yield a print at 3264/72 by 2448/72, that’s a 45 by 34 inch image if you printed it.

If you changed to 300dpi it would print at 3264/300 etc., about an 11 by
8.75 inch print but note the pixel count has not changed at all. You
have merely specified how many pixels to the inch it will print at.

300dpi is more or less standard for high quality printing, which is why the bloke specified it – but the real question is, how big is the image to be printed?

For a CD cover, you’re looking at about a 5×5 inch – roughly – print size, so the question becomes ‘how many pixels do I need to print a 5×5 image at 300 dpi?’ Answer: 5 inches times 300 pixels per inch is 1,500 pixels. But your image is larger than that at 3264 x 2448 pixels, so you will need to reduce your pixel count by downsizing the image to 1500×1500 pixels. Then, if you specify 300 dpi, the image will be 5×5 inches.

You will need to refine my ball-park size estimates, but the idea should be clear.

And don’t forget to work on a copy of the original image, not the original!

Colin D.

"Colin.D" wrote in message

Wolf wrote:

hi
Need to print some cd covers.
The print company guy has confused me- says he needs images at 300dpi. I tell him that mine are 72 dpi (3264 x 2448 pixels from camera image) and he says that’ll be Ok.

Could’t I just upscale the image in PS to 300dpi?

I don’t beleive that my camera, Panasonic fz30, will do 300 dpi (I’ll read the instruction book if i can find it!! )
Can some one post a website or advise how I can understand the difference.

There’s a lot of confusion about dpi. Fact is dpi – dots per inch – is a printer function, and can be changed in PS without affecting the image at all. Currently, your 3264 x 2448 image at 72dpi would yield a print at 3264/72 by 2448/72, that’s a 45 by 34 inch image if you printed it.
If you changed to 300dpi it would print at 3264/300 etc., about an 11 by
8.75 inch print but note the pixel count has not changed at all. You have
merely specified how many pixels to the inch it will print at.
300dpi is more or less standard for high quality printing, which is why the bloke specified it – but the real question is, how big is the image to be printed?

For a CD cover, you’re looking at about a 5×5 inch – roughly – print size, so the question becomes ‘how many pixels do I need to print a 5×5 image at 300 dpi?’ Answer: 5 inches times 300 pixels per inch is 1,500 pixels. But your image is larger than that at 3264 x 2448 pixels, so you will need to reduce your pixel count by downsizing the image to 1500×1500 pixels. Then, if you specify 300 dpi, the image will be 5×5 inches.
You will need to refine my ball-park size estimates, but the idea should be clear.

And don’t forget to work on a copy of the original image, not the original!

Colin D.

Colin D’s answer is correct and he has explained it very well.

However you do not really need to reduce the size of your image to 1500 x 1500 pixels. You could, if you wanted to, or were asked to, but you don’t need to.

The printing people would only have problems if your image did not provide enough of a pixel count, and it has more than enough.

Roy G

Colin’s answer should be FAQ.

But since when is 300dpi "high quality"? What happened to 1200?

John J, very confused, asked:

Colin’s answer should be FAQ.

But since when is 300dpi "high quality"? What happened to 1200?

1200 what? Certainly not dpi.
Like the topic of the thread.

"Dave" wrote in message

John J, very confused, asked:

Colin’s answer should be FAQ.

But since when is 300dpi "high quality"? What happened to 1200?

1200 what? Certainly not dpi.
Like the topic of the thread.

This is certainly a consequence of using dpi instead of ppi.

I am sure the original poster was meaning pixels, and I replied about pixels, but deliberately did not mention dpi.

It is very common, if incorrect, for people to use dpi, (dots per inch), when describing the number of pixels per inch in the image.

John J may be deliberately having a go at the original misuse of dpi, or may be confusing ppi / dpi with the printer output of ink drops per inch.

In any case I use an Epson and it works in multiples of 360 drops per inch for print quality – 360 – 720 – 1440 – 2880.

Any of those settings can be selected irrespective of the number of pixels per inch (ppi) in the image file.

Roy G

"Roy G" wrote in message

John J may be deliberately having a go at the original misuse of dpi, or may be confusing ppi / dpi with the printer output of ink drops per inch.

I probably was confused! A few years ago when doing negatives for printing, the plate maker used the expression "1200". Very high resolution negatives (stochastic dithered, not half-tone) that was then applied in conventional B&W silver/gel contact printing. So that was lines-per-inch? Line/Pairs per inch? 1200 LPI?

Doesn’t matter now. The pic wasn’t so good anyway.

Dave wrote:

John J, very confused, asked:

Colin’s answer should be FAQ.

But since when is 300dpi "high quality"? What happened to 1200?

1200 what? Certainly not dpi.
Like the topic of the thread.

Ok, a little more clarification …

an image is measured in so many pixels, like 2000 x 3000 gives a 6 megapixel image.

Pixels in this sense are dimensionless, i.e. they are not related to any physical size. (I know the sensor has a physical size, but the image it produces is dimensionless.)

When it comes to printing or displaying an image, the size it prints/displays at is set by the pixels-per-inch (ppi) parameter. A 2000×3000 pixel image printed at 300 ppi will yield a 6.66 x 10 inch print. Why? because 2000 pixels at 300 ppi is 2000/300 = 6.67 inches, and 3000/300 = 10 inches.

Change the ppi and the print size changes proportionally – simple arithmetic.

It is generally accepted that an image printed at 300 ppi is adequately high quality. But printers are said to print at 2,880 or even 4,800 dpi, so how does that work?

Well, modern printers have what is called a native resolution. For Canon printers it is 600 ppi, and for Epson it is 720 ppi. If you feed your printer with a 300 ppi image, the printer driver will resample the image to 600 or 720 ppi depending on the printer. But a Canon (for example) printer will print at 4,800 x 2400 dpi – dots per inch. That is ink dots laid down by the printer, not pixels. How come? because the printer lays down many dots to make up one pixel – in Canon’s case, 32 ink dots in an 8 x 4 matrix to make one pixel of the image.

This many-dot system has two advantages; it makes for smoother tonal gradations, and it allows mixing of different-colored inks within the 32-dot pixel to produce exact colors, impossible to do if only one dot was used to print one pixel.

So, recapping:

an image is measured in pixels – no size implied.

An image is viewed or printed at so many pixels per inch – ppi, providing a size to the image.

An image is printed by the printer at so many dots per inch, which is fixed by the printer specs – dpi.

The printer uses many dots of ink to make one pixel.

Have a new respect for your printer. An 8 x 12 inch image is fed to the printer by the printer driver at 600 ppi (regardless of the actual ppi fed to the driver). That’s 8*12*600^2, = 34.560 megapixels. Each of those pixels is made up of 32 ink dots, so that’s 34.560*32, = 1,105.92 megadots – well over a billion dots, every one calculated to produce the right color for every pixel.

I hope that was interesting.

Colin D.

"Roy G" found these unused words:

"Dave" wrote in message

John J, very confused, asked:

Colin’s answer should be FAQ.

But since when is 300dpi "high quality"? What happened to 1200?

1200 what? Certainly not dpi.
Like the topic of the thread.

This is certainly a consequence of using dpi instead of ppi.
I am sure the original poster was meaning pixels, and I replied about pixels, but deliberately did not mention dpi.

It is very common, if incorrect, for people to use dpi, (dots per inch), when describing the number of pixels per inch in the image.
John J may be deliberately having a go at the original misuse of dpi, or may be confusing ppi / dpi with the printer output of ink drops per inch.
In any case I use an Epson and it works in multiples of 360 drops per inch for print quality – 360 – 720 – 1440 – 2880.

Any of those settings can be selected irrespective of the number of pixels per inch (ppi) in the image file.

Roy G

They may be ‘selected’ but then the -=printer=- will interpolate the pixels of the image into that setting. you may or may not get exactly what you had with the image’s dpi marker, viewed in PS or from a printer that matches the marker without interpolation.

Responses much appreciated folks.

"Wolf" wrote in message

hi
Need to print some cd covers.
The print company guy has confused me- says he needs images at 300dpi. I tell him that mine are 72 dpi (3264 x 2448 pixels from camera image) and he says that’ll be Ok.

Could’t I just upscale the image in PS to 300dpi?

I don’t beleive that my camera, Panasonic fz30, will do 300 dpi (I’ll read the instruction book if i can find it!! )
Can some one post a website or advise how I can understand the difference.