why use dot gain compensation curves

[maas]

why use dot gain compensation curves or harmny curves when the colour management of files supplied use ISO profiles which have a TVI compensation build into the profile?

example, for newsprint all files supplied are using the ISOnewsprint26v4 profile, but the resident expert in our company will also run dot gain test on our press, now what doesnt make sense to me is that these files are not created using the ISOnewsprint26v4 profile so in theory are we compensating once to many times for dot gain, by way of embedded profile and by way of dot gain compensation when the plates are imaged (CTP) my question essentiall is can we image the plates linear when creating PDF file using an ISO profile?

[meddington]

The files are being supplied embedded with the ISOnewsprint profile. Therefore you would ideally ensure you are achieving the same tonal response on press. One way to acheive that is through dot gain adjustment of your press via plate curves. Whether or not you could use linear plates depends on the tonal response on press...if you hit the desired tonal response with linear plates, no curves required. Sounds like you resident expert is on the right track to me.

[gordo]

Whether or not you could use linear plates depends on the tonal response on press...if you hit the desired tonal response with linear plates, no curves required.

Just a small quibbily thing - if you are applying a linearizing curve that enables you to get the desired tone response on press then you're effectively using a dot gain curve on the plate.

best gordo

[meddington]

Good point. I should have used the term "uncompensated" rather than "linear".

[maas]

thank you both gents, i guess the term "dot gain" is not always applicable to a process which in essence measures how a device ( i.e. apress) will reproduce a dot, i value you feedback and the explanation regarding 'tonal response" paints a clear picture.

[gordo]

thank you both gents, i guess the term "dot gain" is not always applicable to a process which in essence measures how a device ( i.e. apress) will reproduce a dot, i value you feedback and the explanation regarding 'tonal response" paints a clear picture.

The problem is that industry specifications and guidelines are very poorly written and are very unclear. The result is often confusion and misunderstanding among printers and prepress folks.

best, gordon p