Increasing pixels

[abstracts]

Hi All
Can someone tell me the ways and means of increasing the file size in PS which my camera produces so I can make larger images without compromising quality. My camera only produces a 10.4 MP images, which I don't think is big enough to produce large images. I hope this makes sense.

Cheers Abstracts

[Chris Humphreys]

What you're talking about is upscaling. If you go to Image>Image size you can change the physical image size along with resolution. Make sure that 'resample image' is selected and chose 'bicubic smoother' in the options list at the bottom.

Be aware though that all you are doing is adding in pixels and not actually increasing quality. Photoshop's iterpolation ability is pretty damned impressive all the same but it can only do so much. If you're image is poor quality or off focus to begin with then no amount of pixel peeping is going to improve it.

Cheers

Chris

[abstracts]

Thanks Chris, that sounds exactly what I was after. Is there an accepted 'rule of thumb' as to how much you can upscale.

[Chris Humphreys]

Not really. You could take a 10mp image and upscale to billboard size if you wanted, viewed from 100m it wil probably look ok. But it won't hold up to close scutiny. The point being it depends on how close you're going to be getting to the final image (presumably for print).

I've an A1 print of a shot I took with my old D80 on my wall (10mp), it's fine from normal viewing distance but looks a bit soft from 1ft away.

[ALwin]

Thanks Chris, that sounds exactly what I was after. Is there an accepted 'rule of thumb' as to how much you can upscale.

It will depend on the quality of your images. But other factors come into play with image size:
1) Viewing distance
If the viewer of the image is going to be standing inches away from the image, then of course the quality of the image has to be very good, else if the viewer is standing several meters away (think of those large billboards you see in the streets) the quality can be sacrificed by a certain amount.

2) Resolution and sharpness you need
Increasing image size means adding more pixels to the image, pixels which weren't there. Newer versions of PS and other image tools have better algorithms that handle image resizing. If you want to keep the same dpi/ppi and keep the image sharp then better not to do more than doubling the size. Or if the dpi/ppi is not important, change their values to increase or decrease width/height values. Still, you need to make a judgement call about what you are willing to compromise or sacrifice.

3) Purpose it will serve
Are you planning to put your images on Stock Image websites? They generally ask for large and high quality images?
Are you going to print your images: what paper size? and what paper type?
Upload to the web/view on a screen?

[abstracts]

At the moment, as far as I can tell, my 10 Mp camera produces a TIFF file size of about 28Mb. I would like to increase that to about 50Mb. Do you think that is reasonable. All the images will be of sufficient quality.
Cheers.

[ALwin]

At the moment, as far as I can tell, my 10 Mp camera produces a TIFF file size of about 28Mb. I would like to increase that to about 50Mb. Do you think that is reasonable. All the images will be of sufficient quality.
Cheers.

Ok for what purpose will you use that increased size TIFF file?

If you increase the size of an image by increasing both height and width proportionally, sure it will increase the saved file format size too, which in your case would be a TIFF file. But increase image size, especially raster images which all photographs are, would mean loss of resolution and image quality. The loss increases exponentially with increase in length/width. Photographs are not vector graphics.

Another way a TIFF file size may increase is if you add several layers and image modifications in Photoshop and save the file.

Still I don't see how either of these would improve image quality. The first would only increase the image size and the second is post-processing an image to bring out your vision of the scene you wanted to capture with the camera. And if you took a poorly focused, over/under exposed photo from the beginning, there is nothing you can do in post-processing that will make the photo better.

[abstracts]

Hi Alwin
The increase in file size is to satisfy the requirements of a picture agency who like to have submitted images around 50mb. In the past all my submissions to them have been on slide, so any size issue wasn't a problem, but now they want digital submissions, hence the enquiry.

[ALwin]

Are you sure they are talking about megabytes and not megapixels? 50MB (megabytes) of file size per image sounds like a lot, unless you capture raw with a digital medium format camera like a Hasselblad with 40 megapixel or more sensor.

Sure there are some DSLR's that save RAW files which are more than 20MB in size, such as the 12 megapixel Nikon D700 with 14-bit uncompressed RAW. Converting that RAW file of a D700 to TIFF might create a 40+ megabyte TIFF file, but that's because the image was captured at 14-bits and has all the raw image data.

Which camera are you currently using?

**Was just going through my image archives.
It seems I can get 50megabyte+ TIFF files from a D700 RAW. Without resizing the image at all, just adding data about adjusting brightness, sharpness, colors, etc. Same with the RAW files from my late D90, converting my RAW files to TIFF can get me from 20megabyte TIFF files to 40MB or larger, depending on the amount of image data it has and the adjustment settings during post-processing.

I've also checked, a 1 megabyte or so jpg image file produces a 20megabyte or so TIFF file. The jpg image I tested is 2231px wide by 3310px in height, approximately a 7 megapixel image, with 240dpi.

So perhaps you can get 50+megabyte TIFF files from your 10 megapixel camera, if you shoot RAW. But I wouldn't resize the image to make the TIFF file larger just to meet the necessary file size, especially if you're selling images to a photo stock company or some other. It could potentially degrade the image quality. A 10megapixel camera produces an image of this dimension 3872px x 2592px which is already larger than most commercial LCD screens, doubling that size to get something like 7600px x 5200px just to get a 50megabyte TIFF file is pointless in my opinion. So you may want to think about doing something else to increase file size or talk to the company again and ask why they specifically say it has to be 50megabyte or larger.

[abstracts]

I'm pretty sure they mean mb's. Prior to the digital switch I used to get my slides scanned on a top spec Nikon Coolscan which produced images of between 50-55mb @ 4000 ppi which I then changed to 300, leaving the MB size unaltered, to meet their requirements. As regards camera, it is a Canon 400D.

[ALwin]

Are you taking photos as RAW or jpg?

Was just testing with some old RAW images taken with my recently sold 5DmkII. I can get 50+MB TIFF files from converting the RAW files, the only thing is it requires a lot of post processing data. I even tested with 10megapixal versions of the 5DmkII files instead of it's full 21MP. Without adding data like sharpness, brightness, etc. adjustment values, it doesn't reach 50MB.

But then my workflow may also be different from your's. The primary tool I use is Adobe Lightroom working with RAW files. The only reason I would ever go to TIFF is when I am in Lightroom and wish to edit an image with Photoshop or a plugin installed in Lightroom (e.g. Nik Color Efex Pro) where I have set Lightroom to 'export' to external editing tool as:
-TIFF
-ProPhoto RGB
-16-bits
-240dpi
-no compression

[abstracts]

I shoot in RAW, mess around with the levels etc in CS4's RAW converter, then save it as a TIFF file. Which by doing so, is saved at around 28mb with an image size of 3888x2592.

[ALwin]

Was just doing some tests with a Canon RAW file. When you open it in Photoshop, in the ACR dialogue window, at the bottom where it says something like
"Adobe RGB (1998); 8 bit; 3888x2592; 240dpi..." or "sRGB; 8 bit; 3888x2592; 240dpi..."
click on it and change the depth to 16bit dept channel, and then continue with your normal workflow. See what file size you get.

Changing from 8 bit to 16 bit can drastically increase the file size.

[abstracts]

I shall try that tomorrow as I haven't got the means to change to 16 bit tonight.

[Chris Humphreys]

My 12mp tiff files from RAW conversions are routinely around 60-70mb (16-bit), so you should be looking able to achieve 50 with a 10mp camera. That said it depends entirely on the image content, a photo of a white sheet of paper isn't going to contain the same amount of data as a detailed landscape shot.

It seems incredibly pointless to upscale an image for the sake of it, but it is simply a case of increasing the size in 'image size'. Use the bicubic smoother algorythm and the image will be fine.

Oh and changing an image from 8-bit to 16-bit is even more pointless, bloomin daft stock agency standards if you ask me....