[julez113@yahoo.com]

Hi all,

I am new to this site, but not new to Pentax. I've been shooting with an istDL for 3 years and have now upgraded to a K20D, which is technically much more advanced than I am. I want to enter a photo contest (deadline TODAY) where they require my photographs to be a minimum of 300 dpi with a total file size between 12-17 MB. When I set my K20D to 14.6 at the highest JPEG quality, my images are only 72 dpi x 72 dpi and 6 MB. I know I am technically challenged, but can someone please tell me how to achieve this image quality (300 dpi/12+MB) with the K20D? Thanks,

Julie
aka technically challenged

[patrickt]

300dpi is a printing parameter and isn't set in the camera.
The dpi is set in your software when you prep a photo for printing. That parameter sounds strange for a submission requirement but I'm not expert.

[julez113@yahoo.com]

Thanks Patrick, I told you I was technically challenged. So I can print any of my images, regardless of their JPEG quality or file size from the camera, at that quality. As for the strange parameters, this is actually only the 2nd contest I've entered where I had to be baffled by this requirement, and both of them are relatively small Florida contests -- my local camera store was unable to help me and thought that strange as well.

[Lowell Goudge]

just so you understand completely, the 72 dpi that the pentax photos default to for "printing" has one other impact, specifically the dimensions of the image in inches, when you view the image on the screen.

other than that, the images are scaled to fit the printer DPI when printing anyway

[julez113@yahoo.com]

I guess what I am not understanding is the file size specification of 12-17 MB, and I think that is something I can accomplish also by saving it at that size through Photoshop or the Pentax software. These images are to be displayed as "CollidEscape window film" on windows at a nature center so they need to be able to be enlarged considerably -- however, I thought shooting a focused shot at 14.6 would give me that capability, eh?

[madhurvyas]

Edit the image in Photoshop, edit the image size, set the unit to inches & dpi or ppi to 300, you will have a 300 dpi image, & it would be large enough.

When we talk about resolution or Megapixel its the dimension of the image in pixels:
~1MP= 1200x900
its your images widht & height which defines the Megapixel or resolution.
When we talk about printing here we have DPI(dots per inch) or PPI (pixel per inch)
So if your printer prints in 72 DPI/PPI 1MP image print size would be 16"x12"
Now if you change it to 300DPI same image would be 4"x3"

So thats the relation between DPI & MP

Hope thats clear

[Entropy]

I guess what I am not understanding is the file size specification of 12-17 MB, and I think that is something I can accomplish also by saving it at that size through Photoshop or the Pentax software. These images are to be displayed as "CollidEscape window film" on windows at a nature center so they need to be able to be enlarged considerably -- however, I thought shooting a focused shot at 14.6 would give me that capability, eh?

Do they specify the dimensions of these displays?

Multiply the output dimensions by 300 dpi to find out the required resolution.

e.g. 6"x4" at 300 DPI = 1800x1200

[julez113@yahoo.com]

OK, I think I'm getting it (or that's just a headache!). The size they are reproducing to is (they think!) 34" x 28"

[procyon]

With these dimensions and DPI the required megapixels would be over 85 ....
Ahem .... they just don't know what they want themselves.
Probably they just want a jpeg file with "300" written in the file as the DPI.
Technically you could achieve it with the cheapest webcam or 640x480 image from a cellphone

[reknelb]

The only time i've ever heard the requirement for 300 dpi is when the picture was going to be printed in a magazine. They also wanted the color space to be adobe rgb instead of sRGB. Are they going to make a magazine/catalogue/calender of some sort whith the winners perhaps??

[KrisK10D]

I just did some testing on jpg's from a K10D.

I found to make the image 34x28 inches at 300dpi, I ended up with an enormous file of over 240M.

To make the file size you need you'll have to make changes in the JPEG Options window that opens when you save the file, in the Image Options Quality area.

I only have 1 gig ram so my computer was struggling at Quality #7 and I had to change the Format Options to Baseline "Standard" for it to save at all. At Quality 10, I ended up with a 10.1M file, and at Quality 11 it was 15.6M. I would imagine that at Quality 12 it would be too big for your purposes.

Hope this helps!

[jeffkrol]

Hi all,

I am new to this site, but not new to Pentax. I've been shooting with an istDL for 3 years and have now upgraded to a K20D, which is technically much more advanced than I am. I want to enter a photo contest (deadline TODAY) where they require my photographs to be a minimum of 300 dpi with a total file size between 12-17 MB. When I set my K20D to 14.6 at the highest JPEG quality, my images are only 72 dpi x 72 dpi and 6 MB. I know I am technically challenged, but can someone please tell me how to achieve this image quality (300 dpi/12+MB) with the K20D? Thanks,

Julie
aka technically challenged

Send them a TIFF.... Anyways I THINK they got it wrong as to MB vs MP. I THINK they meant 12-17 MP at 300 dpi.....
File sizes will depend on soooo many factors that it is really not that important.
As to the 300dpi, as mentioned, it is only a marker.
3 things to note on this image: W a 6MP camera at 300 dpi it would print at 10.1 x 6.7 inches vs 100 dpi which would print at 30.38 x 20.22 inches...
NOTE the "Maintain original size" check box. This is important and only means that I have NOT resampled and altered my data. The ONLY thing it did is bascially make the "dots" bigger....
Bigger dots bigger image...NOTE file size has not changed (this is a 16bit TIFF so file is huge compared to a jpg 36.8MB)
As to why I believe they meant MP instead of MB is because IF you want to enlarge the image to 30.38 X 20.22 AND have it 300dpi you must ADD dots (3x more dots BTW), which will be created in some manner. This completely changes the picture and data...
So I believe thay just want more "dots" (i.e. MP) so as not to have to create as many "new" dots from the old.
To create a 34x28 image from a 6MP camera would involve tripeling (or so) your orig dot count (they would be created by interpolation using 1 of many types of formulas).. At 12-17 MP you would only need to double and this would maintain quality. Actually they would probably print at 150dpi and then not have to "upsample" much if at all .
Lower MP count and you have to change the actual image.
ADDENDUM for print size comparisons:
12mp image at 4000×3000 pixels would make a:
13.3” x 10” print at 300dpi
20” x 15” print at 200dpi
25” x 18.7 print at 160dpi.
26.6" X 20" print at 150dpi
39.9" X 30" print at 100dpi