DPI woes, how do I sort this please?
Posted 13/12/2013 - 16:15
Link
Its one to add to the long list of clear explanations of the age-old dimension / pixel / dots misunderstanding!
I will certainly study it in greater detail, but for now the first paragraph is probably the most significant ... it is clearly a highly size-reduced or compressed JPG version intended for email, or small web display.
Louise, it is important when saving a new version of your shots in photo editing software to always choose the 'Maximum' quality option for JPEGs intended to be printed. If possible I'd try and go back through your workflow starting from when you opened the shot into the first software from the camera (or where it was first copied onto your computer).
If you are making edits to this shot and intending to continue with more work later, or you want to edit something more using a different programme, then try and 'save as' a TIFF file, and choose 'No Compression'. This will ensure that the size does not reduce. You use this TIFF file to do the edits, saving at the end again with 'No Compression'.
Then the last step is to open the final TIFF in your chosen software and 'Save As' a 'maximum quality' JPEG - this will become the final file that you send to the printers. So long as you have only chosen the 'Maximum' quality options and have not changed the dimensions of the image at any point, then the printers should be able to produce the bigger sizes you want.
I will certainly study it in greater detail, but for now the first paragraph is probably the most significant ... it is clearly a highly size-reduced or compressed JPG version intended for email, or small web display.
Louise, it is important when saving a new version of your shots in photo editing software to always choose the 'Maximum' quality option for JPEGs intended to be printed. If possible I'd try and go back through your workflow starting from when you opened the shot into the first software from the camera (or where it was first copied onto your computer).
If you are making edits to this shot and intending to continue with more work later, or you want to edit something more using a different programme, then try and 'save as' a TIFF file, and choose 'No Compression'. This will ensure that the size does not reduce. You use this TIFF file to do the edits, saving at the end again with 'No Compression'.
Then the last step is to open the final TIFF in your chosen software and 'Save As' a 'maximum quality' JPEG - this will become the final file that you send to the printers. So long as you have only chosen the 'Maximum' quality options and have not changed the dimensions of the image at any point, then the printers should be able to produce the bigger sizes you want.
My Guides to the Pentax Digital Camera Flash Lighting System : Download here from the PentaxForums Homepage Article .... link
Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60/X Flashes & V6/V6II Transceiver
Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60/X Flashes & V6/V6II Transceiver
Posted 13/12/2013 - 17:23
Link
Agreed with all that but why not send the lossless TIFF file to the printers?
John K
Posted 13/12/2013 - 17:52
Link
I was thinking of online web printing services, and uploading a fair number - my TIFFs are usually about 80mb, not really practical for uploading a lot.
But I suppose if you're using a CD or DVD and sending it by post then the TIFF is an option. The question is would it be any real advantage? Most of the online services I've used generally only take JPEGs I think. Certainly I've never been given any indication that the JPEGs are a disadvantage - all my shots give an 'optimum' rating when the web service assess them for the chosen print sizes, and this includes prints of 100cm x 70cm. This would be for JPEGs of the minimal compression setting and in the range of 8 - 14 mb file size.
But I suppose if you're using a CD or DVD and sending it by post then the TIFF is an option. The question is would it be any real advantage? Most of the online services I've used generally only take JPEGs I think. Certainly I've never been given any indication that the JPEGs are a disadvantage - all my shots give an 'optimum' rating when the web service assess them for the chosen print sizes, and this includes prints of 100cm x 70cm. This would be for JPEGs of the minimal compression setting and in the range of 8 - 14 mb file size.
My Guides to the Pentax Digital Camera Flash Lighting System : Download here from the PentaxForums Homepage Article .... link
Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60/X Flashes & V6/V6II Transceiver
Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60/X Flashes & V6/V6II Transceiver
Posted 14/12/2013 - 09:11
Link
Quote:
Sounds like your editing software has produced an emailable image rather than a printable image
I am using Fast Stone at the moment and I found where I can change the DPI, so I have been putting 240-300: is that right or should I be putting something else?
Sounds like your editing software has produced an emailable image rather than a printable image
Always be kind to people
link
https://www.facebook.com/pages/Photographs-by-an-angel/262352847143059
link
link
https://www.facebook.com/pages/Photographs-by-an-angel/262352847143059
link
Posted 14/12/2013 - 09:52
Link
That's fine, should make perfectly good prints up to A3.
Best regards, John
Posted 14/12/2013 - 14:55
Link
ppi, not dpi. Images are measured in ppi (pixels per inch) but, yes, pixel dimensions will have to be satisfactory.
ppi has a very real effect on the image. If you print a 72ppi image straight from a 16MP camera it will be an enormous print, printed at a very poor 72 pixels per inch. On an A3 piece of paper you would also only print part of the image.
If you change the figures to say 300ppi the picture dimensions will shrink to about A3, so now your whole picture will be printed at the correct resolution.
Now the printer lays down dots of ink per inch (dpi) so the more dpi the printer uses the more detail will be printed. But whatever dpi the printer uses it will be trying to print a 300ppi image.
ppi has a very real effect on the image. If you print a 72ppi image straight from a 16MP camera it will be an enormous print, printed at a very poor 72 pixels per inch. On an A3 piece of paper you would also only print part of the image.
If you change the figures to say 300ppi the picture dimensions will shrink to about A3, so now your whole picture will be printed at the correct resolution.
Now the printer lays down dots of ink per inch (dpi) so the more dpi the printer uses the more detail will be printed. But whatever dpi the printer uses it will be trying to print a 300ppi image.
Best regards, John
Posted 14/12/2013 - 19:40
Link
Quote:
Sounds like your editing software has produced an emailable image rather than a printable image
Hi I am using fast stone at present. In the edit tab I click on set DPI and at the moment I have been putting 240-300. Is this the right size to put please?
Sounds like your editing software has produced an emailable image rather than a printable image
Always be kind to people
link
https://www.facebook.com/pages/Photographs-by-an-angel/262352847143059
link
link
https://www.facebook.com/pages/Photographs-by-an-angel/262352847143059
link
Add Comment
To leave a comment - Log in to Pentax User or create a new account.
6794 posts
17 years
Nottingham
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