DPI woes, how do I sort this please?

Just sticking to the PPI issue (the OP had 72), my own experiences with printing services suggests that this figure should be irrelevant to the printers, at least as far as the file supplied to them is concerned.

What would matter is the total amount of pixel data. So long as the camera had been set to its maximum 'resolution' setting, there will be plenty of pixel data in total for all standard print outputs, at least A3 I'd have thought.

What should happen is that the print service's software will adjust the file to give the best PPI figure to match the ideal DPI for the actual print -we don't really need to bother with these details I believe, unless we are printing our own shots at home on an inkjet machine.

Unless there was an issue with the amount of 'total pixel data' suppled in the file, (for example there was not enough for the requested print sizes to be printed at good quality), I don't understand why the printer is questioning the OPs 'DPI' figure (they mean PPI, right?)

Louise, just check that your K30 is set to its maximum resolution setting (that would be 16mp is that right?) - your shots will then be recording the maximum amount of pixel data, and any print service should be able to output big prints - the 'DPI' (PPI) of the files from the camera should not matter at all.

If you can't get a clear explanation from this particular print service of what the problem is for them, then just send your shots somewhere else.

Quality print services will specify the optimum file details for a given size of print. This does include the ppi figure. Letting the printer company resize is less than optimum, as long of course as you know what you are doing.

I have had a look in Picture monkey,the help screen said it can save in 3 sizes up to 16mp, there is a gear wheel above the photo that will let you change the size.

It doesn`t say what resolution it saves at but would be fairly high being 16mp.

Jack.

Got some on a hard drive, but some of these I put on a memory stick. Will be able to get them printed, but I will still also be stuck with the same problem.

How do I get to that in Picassa please?

When it uploads it goes straight into Picture Motion browser which came with my camera. I then transfer it to Picassa.

What is not clear to me then is why should we assume that a photographer performing resizing on a home computer would produce better results than a commercial software package connected to a specfic professional grade printing device, operated by an experienced technician?

Because Nigel the auto correction that happens in the lab isn't the same as doing it yourself. In the same way a commercial black and white print won't be as good as your own work in the darkroom. This all assumes you have the necessary level of skill.

The better you get the more you will want to control the process yourself.

Is it really to do with the photographers skill and experience? I'd have thought the steps involved in carrying out resizing processes in Photoshop could be read about and followed fairly easily by most - you just have to understand the concepts of the best method to select whether increasing or reducing size and the appropriate sharpening options.

Surely it is really the underlying technology and processing algorithims employed in the different softwares that is more critical? That is why I am suggesting that commercial software, linked to professional grade equipment, and set up by trained and experienced technicians who produce these particular kinds of prints all day, might be better.

Of course, I'm talking about limited print runs of large sizes, individually controlled by the lab, not large-scale mass runs of 7'x5's.

The printing company should change to DPI themselves to match the output size to the image size. whether its 72dpi,300dpi or 3200dpi is irrelevant.
If you want, say, 10x8 inch print from a 5000 x 4000 pixel image, and the printer prints at 300dpi the printers would need to reduce the image to 3000 x 2400 pixels. It doesn't matter what the original resolution was, it doesn't enter the calculation!

Can I just ask the most obvious questions, the files that you took to the print shop, what size were they? You should be able to check by right click on the file and check properties and click on details tab and look for image size. Second what size did you request to print I can't see this mentioned? Let us first check if in fact the attainable ppi that can be obtained regardless of settings.
Best regards

Only the ability to print large, decent resolution images, which was the whole point of the original post.

There is one obvious situation where doing it yourself will almost certainly produce better results - or at least, be closer to the result you intend. Many/most print sizes offered by commercial printers are not the same aspect ratio as the sensor in your camera, so images will need resizing and/or cropping to fit the print size.

Wouldn't you rather decide which bits of your image are cropped off? You might prefer to keep the top half of Auntie Flo's head on the print.

Andrew

According to the printers when looking on the memory stick, they were 72dpi. The size on the disk when I clicked on properties is 156 KB (159,828 bytes) what ever that means.

A4 or equivalent. But according to the size it was, I had to have it smaller.

I tried to work on a file through Gimp, I pressed save as and tried to grab the file through Picassa but it said the file was obtainaible. When I go to the file in my documents itkeeps loading up Gimp instead of the picture. can you tellme what I am doing wrong?

I'm experiementing with Fast Stone at the moment.

156KB?

Lol.

What is the image dimensions? For example in the example below, it's 4928 x 3264 - that is the original image size and will be plenty for a really large print (irrespective of the essentially meaningless 'dpi' figure - lol)

No it makes no difference - a 4928 x 3264 pixel image is the same size no matter whether it's 72 or 300 'dpi'!

If the JPG file was 156kB then it probably was a tiny image!
Sounds like your editing software has produced an emailable image rather than a printable image


Pixel dimensions is the criteria for printing.

Regarding DPI (or perhaps more accurately PPI) there are two ways it is used:

1) Where the print company tells you what DPI your image is. For this, they have calculated the DPI value with the formula: pixels ÷ width-in-inches.

For example, if you have given them a full K-30 image (4928 pixels wide) and you want it printed 10 inches wide, then the DPI = 4928 ÷ 10 = 492 DPI

In this scenario they are giving you an indicator of how detailed the printed image will look. You'll need at least 300DPI for a high quality print (so a K-30 image at 4928 can be printed up to 16 inches across - 4928 ÷ 300 = 16.4")

They will ignore the embedded EXIF value for DPI (i.e. what was set in Photoshop and only use the pixel dimensions)


2) Where the DPI figure is embedded in the EXIF information of the JPG.
This is largely ignored

But if you are doing publishing this value is taken into account when placing an image into DTP pages. For example, InDesign will automatically scale the imported image based on the DPI embedded value and the pixel dimensions. The width will start off as width-in-inches = pixels ÷ DPI-value-in-EXIF
Of course, it can be scaled from there. But setting a 'correct' DPI is helpful not to annoy the publisher (Imaging them placing a 4928 pixel image that was indicated at 72dpi - they'd end up with a 68 inch wide image that they would have to rescale! It gets really, really irritating when you have tens of images to place on a prepress document :roll


But again, for Louise's issue - this is scenario 1.

Matt