Resizing images from scan size to digital negatives (sharpness issue)

[Fulvio]

Hi... I've been experimenting with digital negatives since 8 months. I've read tons of technical data on how to make digital enlargements (books, articles, internet...). Now I can produce exicting images with my Epson r2400 and with several kinds of processes. I'm pleased with the tonal range of my images. But sometimes I'm disappointed with print sharpness. The images are fine, but I believe that sharpness can be improved a lot. I'm using a bostick & sullivan contact printing frame & Agfa copyjet negatives, which are very similar to Pictorico OHP. I normally print negatives at 360 dpi. Recently I've switched also to 600 dpi, without much difference. The UV light source normally used is an array of 6 BLB tubes, ca. 40cm distant from the glass. Some other time I use the light of an enlarger for those processes that don't require UV lighting. Initially I was thinking that the problem could be the diffused light form the UV box... But then I don't see any sharpness improvement with the pointing light from the enlarger. So I guess that the light source doesn't make a noticeable difference in terms of sharpness. Then I thought it could be the negative. Although finely printed, perhaps there's something wrong with the scanning-resizing-outputting process of my images. In other words: let's suppose I scan a 120 / 6x6 negative at 2400dpi (I use a 4990 Epson Scanner). The target negative will have a size of 15x15 cm. I have necessarly to resize the negative to 15x15 cm and 360 (or 600?) dpi. I'm no Photoshop/Printer expert, so I guess in this step there's some mistake. Which is the optimal way to resize a scanned negative in order to print it enlarged on a digital negative? Just go in Photoshop and select Image-Resize and press the button? Should I do something with the unsharp mask filter? If yes when? The original scan size should be related to the final print size? How to make the digital negative as sharp as possible so it will print sharp on the final print on paper after exposure?

many thanks

[donbga]

Hi... I've been experimenting with digital negatives since 8 months. I've read tons of technical data on how to make digital enlargements (books, articles, internet...). Now I can produce exicting images with my Epson r2400 and with several kinds of processes. I'm pleased with the tonal range of my images. But sometimes I'm disappointed with print sharpness. The images are fine, but I believe that sharpness can be improved a lot. I'm using a bostick & sullivan contact printing frame & Agfa copyjet negatives, which are very similar to Pictorico OHP. I normally print negatives at 360 dpi. Recently I've switched also to 600 dpi, without much difference. The UV light source normally used is an array of 6 BLB tubes, ca. 40cm distant from the glass. Some other time I use the light of an enlarger for those processes that don't require UV lighting. Initially I was thinking that the problem could be the diffused light form the UV box... But then I don't see any sharpness improvement with the pointing light from the enlarger. So I guess that the light source doesn't make a noticeable difference in terms of sharpness. Then I thought it could be the negative. Although finely printed, perhaps there's something wrong with the scanning-resizing-outputting process of my images. In other words: let's suppose I scan a 120 / 6x6 negative at 2400dpi (I use a 4990 Epson Scanner). The target negative will have a size of 15x15 cm. I have necessarly to resize the negative to 15x15 cm and 360 (or 600?) dpi. I'm no Photoshop/Printer expert, so I guess in this step there's some mistake. Which is the optimal way to resize a scanned negative in order to print it enlarged on a digital negative? Just go in Photoshop and select Image-Resize and press the button? Should I do something with the unsharp mask filter? If yes when? The original scan size should be related to the final print size? How to make the digital negative as sharp as possible so it will print sharp on the final print on paper after exposure?

many thanks

All scanned images need some amout of resharping. So edit your image as necessary. Resize the image to the desired output size at 360 dpi using bicubic smoother. Finally use the Unsharp mask to sharpen the image.

Also you did not mention what printer dpi you are using to print your negative. For silver gelatin use the highest dpi setting availabe in the printer driver settings. For the 2400 I think the Quality Setting is tagged Photo RPM which should yield 5760 dpi output,

Good luck

[Fulvio]

All scanned images need some amout of resharping. So edit your image as necessary. Resize the image to the desired output size at 360 dpi using bicubic smoother. Finally use the Unsharp mask to sharpen the image.

Also you did not mention what printer dpi you are using to print your negative. For silver gelatin use the highest dpi setting availabe in the printer driver settings. For the 2400 I think the Quality Setting is tagged Photo RPM which should yield 5760 dpi output,

Good luck

mmm Yes I tried some unsharp masking after resizing, with different settings (best one probably radius 1 pixel, range 100-400%... But I think it is not enough yet. Normally I print at 360 dpi, as suggested in Mark Nelson PDN and other literature. I've tried also 600 dpi with any noticeable improvement (maybe a little bit, but unsure). I always print in Photo RPM quality on glossy media with my R2400 and switch off high speed printing (I delay the printing output as well to prevent pizza wheels marks).

[donbga]

mmm Yes I tried some unsharp masking after resizing, with different settings (best one probably radius 1 pixel, range 100-400%... But I think it is not enough yet. Normally I print at 360 dpi, as suggested in Mark Nelson PDN and other literature. I've tried also 600 dpi with any noticeable improvement (maybe a little bit, but unsure). I always print in Photo RPM quality on glossy media with my R2400 and switch off high speed printing (I delay the printing output as well to prevent pizza wheels marks).

You should have no pizza wheel marks with Pictorico OHP but I don't know about Agfa-jet.

[Fulvio]

You should have no pizza wheel marks with Pictorico OHP but I don't know about Agfa-jet.

no I don't, but still I print slowly (no less than 30 sec delay) to avoid any chances...

[donbga]

no I don't, but still I print slowly (no less than 30 sec delay) to avoid any chances...

Pictorico needs no delay for drying.

[Fulvio]

Pictorico needs no delay for drying.

well alright, maybe also Agfa Copyjet... Before that I used Canson transparencies which were not as good as Agfa (they were fair and cheap anyway). But I don't think that all this has something to do with sharpness.

thanks anyway